feeling sad and unhappy

homesick

home·sick [homesick homesickness]   [ˈhəʊmsɪk]    [ˈhoʊmsɪk]  adjective
sad because you are away from home and you miss your family and friends
• I felt homesick for Scotland.
Derived Word: homesickness  
Example Bank:
• She felt homesick for her country.

• She was beginning to get a bit homesick.

grim

grim [grim grimmer grimmest]   [ɡrɪm]    [ɡrɪm]  adjective (grim·mer, grim·mest)
1. looking or sounding very serious
• a grim face/look/smile
• She looked grim.
• with a look of grim determination on his face
• He set about the task with grim concentration.

• grim-faced policemen

2. unpleasant and depressing
• grim news
• We face the grim prospect of still higher unemployment.
• Despite the grim forecast, the number of deaths was slightly down on last year.
• The outlook is pretty grim.
• This latest attack is a grim reminder of how vulnerable our airports are to terrorist attack.
• Booth paints a grim picture of life in the next century.
• a grim struggle for survival

• Things are looking grim for workers in the building industry.

3. (of a place or building) not attractive; depressing
• The house looked grim and dreary in the rain.

• the grim walls of the prison

4. not before noun (BrE, informal) ill/sick

• I feel grim this morning.

5. not usually before noun (BrE, informal) of very low quality
• Their performance was fairly grim, I'm afraid!
Idiom: hang on for grim death
Derived Words: grimly ▪ grimness
See also: hang on for dear life  
Word Origin:
Old English, of Germanic origin; related to Dutch grim and German grimm.  
Example Bank:
• James had some rather grim news.
• The accident serves as a grim reminder of what drinking and driving can do.
• There was a grim smile on her face as she approached.

• They clung on to the edge of the boat with grim determination.

down in the ˈmouth
unhappy and depressed
Oxford Advanced Learner's Dictionary 9th edition © Oxford University Press, 2015

adjective
very sad or making you feel sadness
Syn:  mournful, Syn: sombre
• melancholy thoughts/memories
• The melancholy song died away.  
Word Origin:
Middle English: from Old French melancolie, via late Latin from Greek melankholia, from melas, melan- ‘black’ + kholē ‘bile’, an excess of which was formerly believed to cause depression.  
Example Bank:
• She began to feel more and more melancholy.
• He was a tall man with a long, melancholy face.
• I grew very melancholy and weary.

• She was in a melancholy mood.

sad

sad [sad sadder saddest]   [sæd]    [sæd]  adjective (sad·der, sad·dest)

 
UNHAPPY
1. unhappy or showing unhappiness
• ~ (to do sth) We are very sad to hear that you are leaving.
• ~ (that…) I was sad that she had to go.
• ~ (about sth) I felt terribly sad about it.
• She looked sad and tired.
• He gave a slight, sad smile.

• The divorce left him sadder and wiser (= having learned from the unpleasant experience).

2. that makes you feel unhappy
• a sad story
• ~ (to do sth) It was sad to see them go.
• ~ (that…) It is sad that so many of his paintings have been lost.
• We had some sad news yesterday.
• He's a sad case— his wife died last year and he can't seem to manage without her.
• It will be a sad day for all of us if the theatre is forced to close.

• Sad to say (= unfortunately) the house has now been demolished.  

UNACCEPTABLE

3. unacceptable; deserving blame or criticism
Syn:  deplorable
• a sad state of affairs
• It's a sad fact that many of those killed were children.

• It's a sad reflection on life that it takes danger and suffering to bring people closer together.  

BORING

4. (informal) boring or not fashionable
• You sad old man.

• You'd have to be sad to wear a shirt like that.  

IN POOR CONDITION

5. in poor condition
• The salad consisted of a few leaves of sad-looking lettuce.
see also  sadly, sadness  
Word Origin:
Old English sæd ‘sated, weary’, also ‘weighty, dense’, of Germanic origin; related to Dutch zat and German satt, from an Indo-European root shared by Latin satis ‘enough’. The original meaning was replaced in Middle English by the senses ‘steadfast, firm’ and ‘serious, sober’, and later ‘sorrowful’.  
Thesaurus:
sad adj.
1.
• I felt so sad that she had to go.
unhappy • • miserable • • gloomy • • glum • • depressed • • heartbroken • |informal down • |especially written mournful • • despondent • |literary melancholy •
Opp: happy
sad/unhappy/miserable/gloomy/glum/depressed/heartbroken/despondent about sth
sad/unhappy/miserable/depressed/heartbroken when/that…
feel sad/unhappy/miserable/gloomy/depressed/despondent
look sad/unhappy/miserable/mournful/gloomy/glum/depressed
Sad or unhappy? You usually feel unhappy about sth that has happened to you; you feel sad about sth that has happened to sb else. A period of your life can be unhappy; sth that you see or hear can be sad
• an unhappy childhood
• sad news
2.
• The sad truth is, he never loved her.
pathetic • • painful • • upsetting • • distressing • • tragic • • heartbreaking •
sad/painful/upsetting/distressing/tragic/heartbreaking for sb
sad/painful/upsetting/heartbreaking to do sth
a sad/pathetic/tragic/heartbreaking story  
Example Bank:
• I called Mum, sounding all sad and pathetic.
• It would be a pretty sad individual who didn't feel that they were unique.
• She was still feeling very sad about her father's death.
• This music always makes me sad.
• a deeply sad occasion
• a rather sad story
• an extremely sad story
• He's a sad case— his wife died last year and he can't seem to manage without her.
• I find it sad that our open spaces are disappearing.
• It is sad that so many of his paintings have been lost.
• It was sad to see them go.
• It's a sad fact that many of those killed were children.
• It's a sad reflection on life that it takes danger and suffering to bring people closer together.
• It's a terribly sad story.
• Sad to say the house has now been demolished.
• The divorce left him sadder and wiser.
• The sad truth is, he never loved her.
• This sad state of affairs does not have to continue.

• We are sad to hear that you are leaving.

lonely

lone·ly [lonely lonelier loneliest]   [ˈləʊnli]    [ˈloʊnli]  adjective (lone·lier, lone·li·est)
1. unhappy because you have no friends or people to talk to
• She lives alone and often feels lonely.

• As I didn't speak the language I grew lonelier and lonelier.

2. (of a situation or period of time) sad and spent alone

• all those lonely nights at home watching TV

3. only before noun (of places) where only a few people ever come or visit
Syn:  isolated
• a lonely beach
Derived Word: loneliness  
Word Origin:
late 16th cent.: from lone  + -ly.  
Thesaurus:
lonely adj.
1.
• She lives alone and often feels lonely.
alone • • isolated • • desolate • |written forlorn •
feel lonely/alone/isolated/desolate/forlorn
Lonely or alone? Alone is slightly more informal than lonely and cannot be used before a noun.
2. usually before noun
• He thought of those lonely nights watching TV.
solitary • • alone • • by yourself • • on your own •
a lonely/solitary existence/life/walk  
Which Word?:
alone / lonely / lone
Alone, and on your own /by yourself (which are less formal and are the normal phrases used in spoken English), describe a person or thing that is separate from others. They do not mean that the person is unhappy: ▪ I like being alone in the house. ◊ ▪ I’m going to London by myself next week. ◊ ▪ I want to finish this on my own ▪ (= without anyone’s help) ▪.
Lone/solitary/single mean that there is only one person or thing there; lone and solitary may sometimes suggest that the speaker thinks the person involved is lonely: ▪ a lone jogger in the park ◊ ▪ long, solitary walks
Lonely (NAmE also lonesome) means that you are alone and sad: ▪ a lonely child ◊ ▪ Sam was very lonely when he first moved to New York. It can also describe places or activities that make you feel lonely: ▪ a lonely house  
Example Bank:
• It gets pretty lonely here in winter.
• She felt oddly lonely without her books.
• She was desperately lonely at school.
• As I didn't speak the language I grew lonelier and lonelier.
• He thought back to all those lonely nights at home watching TV.
• The support they give to lonely old people is invaluable.

• There are times when I feel very lonely.