could

[ kood; unstressed kuhd ]

auxiliary verb

1. a simple past tense of can ¹.
2. (used to express possibility):

   I wonder who that could be at the door. That couldn't be true.

3. (used to express conditional possibility or ability):

   You could do it if you tried.

4. (used in making polite requests):

   Could you open the door for me, please?

5. (used in asking for permission):

   Could I borrow your pen?

6. (used in offering suggestions or advice):

   You could write and ask for more information. You could at least have called me.

could

/ kʊd /

verb

1. used as an auxiliary to make the past tense of can 1
2. used as an auxiliary, esp in polite requests or in conditional sentences, to make the subjunctive mood of can 1

   she'd telephone if she could

   could I see you tonight?

3. used as an auxiliary to indicate suggestion of a course of action

   you could take the car tomorrow if it's raining

4. often foll by well used as an auxiliary to indicate a possibility

   he could well be a spy

Usage Note

See care.

Word History and Origins

Origin of could¹

First recorded in 1450–1500; alteration of late Middle English coude, coud, Old English cūthe; modern -l- from would ¹, should

Word History and Origins

Origin of could¹

Old English cūthe; influenced by would , should; see can ¹

Idioms and Phrases

see can (could) do with ; see with half an eye, could . Also see under can ; couldn't .

Example Sentences

This could provide even more detailed information about brain function and disease states.

From Science Daily

Inevitably, there will be questions about the health risks posed by this new compound, which could not be previously evaluated in any toxicity studies.

From Science Daily

This means that such a mutation could affect the amount of several ingredients at the same time.

From Science Daily

They then used a vacuum pump to concentrate the DNA on a filter, which they tested to confirm that they could extract DNA from the samples and obtain accurate results.

From Science Daily

A warmer, wetter climate could lead to rapid melt.

From Science Daily

Related Words

• commit
• manage
• take care of