weed

I. weed¹ /wiːd/ BrE AmE noun
[Language: Old English; Origin: weod]
1. [countable] a wild plant growing where it is not wanted that prevents crops or garden flowers from growing properly:
the constant battle against weeds
2. [uncountable] a plant without flowers that grows on water in a large green floating mass ⇨ seaweed
3. [countable] British English informal someone who is weak:
Nigel’s such a weed, isn’t he?
4. like weeds in large numbers:
Cars clogged the roads like weeds.
5. the weed informal cigarettes or tobacco
6. [uncountable] old-fashioned ↑cannabis
7. (widow’s) weeds old use black clothes worn by a woman whose husband has died
• • •
THESAURUS
▪ plant a living thing that has leaves and roots and grows in earth, especially one that is smaller than a tree: Don’t forget to water the plants. | Plants grow towards the sun. | Botanists examined plant species from around the world.
▪ herb a small plant that is used to improve the taste of food, or to make medicine: Sprinkle the dish with chopped fresh herbs. | medicinal herbs (=used as medicine) | The shop sells an interesting range of herbs and spices.
▪ weed a wild plant growing where it is not wanted that prevents crops or garden flowers from growing properly: She was pulling up weeds in her garden. | Herbicides can be used to prevent and control weeds.
▪ bulb a root shaped like a ball that grows into a flower or plant: She planted hundreds of daffodil bulbs.
▪ shrub a small bush with several woody stems: flowering shrubs | Rosemary is an evergreen shrub.

Oxford Advanced Learner's Dictionary

weed

weed [weed weeds weeded weeding] noun, verb [wiːd] [wiːd]

noun
1. countable a wild plant growing where it is not wanted, especially among crops or garden plants

• The yard was overgrown with weeds.

2. uncountable any wild plant without flowers that grows in water and forms a green floating mass

3. the weed singular (humorous) tobacco or cigarettes

• I wish I could give up the weed (= stop smoking).

4. uncountable (informal) the drug cannabis

5. countable (BrE, informal, disapproving) a person with a weak character or body
• Don't be such a weed!
Word Origin:
Old English wēod (noun), wēodian (verb), of unknown origin; related to Dutch wieden (verb).
Example Bank:
• Routine maintenance of the garden consists of keeping weeds under control.
• There were weeds pushing up through the gravel.

Derived: weed somebody out

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

weed / wid / noun (PLANT)

C2 [ C ] any wild plant that grows in an unwanted place, especially in a garden or field where it prevents the cultivated plants from growing freely
[ U ] slang →   cannabis
[ U ] UK old-fashioned informal →   tobacco

weed / wiːd / noun [ C ] UK informal disapproving (PERSON)

someone who is thin and physically weak or who is weak in character:

He looks like a real weed in those shorts.

Collins COBUILD Advanced Learner’s English Dictionary

weed

[wi͟ːd]
weeds, weeding, weeded
1) N-COUNT A weed is a wild plant that grows in gardens or fields of crops and prevents the plants that you want from growing properly.
  With repeated applications of weedkiller, the weeds were overcome.
2) N-VAR Weed is a plant that grows in water and usually forms a thick floating mass. There are many different kinds of weed.
  Large, clogging banks of weed are the only problem.
4) N-UNCOUNT: also the N People sometimes refer to tobacco or marijuana as weed. [INFORMAL]
  Two and a half years ago I gave up the evil weed.

Merriam-Webster's Advanced Learner's Dictionary

Merriam-Webster's Advanced Learner's Dictionary:

¹weed /ˈwiːd/ noun, pl weeds
1 [count] : a plant that grows very quickly where it is not wanted and covers or kills more desirable plants
• We pulled weeds from the garden.
• an invasive weed
- see also milkweed, ragweed, seaweed, tumbleweed
2 [noncount] informal : marijuana
• They were smoking weed.
3 the weed chiefly Brit informal : cigarettes and other tobacco products
• She's trying to give up the weed. [=trying to quit smoking]
grow like a weed chiefly US informal : to grow very quickly
• Their business is growing like a weed.
• Look at you! You're growing like a weed!