because

UK: strong: /bɪˈkəz/, weak: /bɪˈkɒz/

US: /bɪˈkɔz, -ˈkʌz/

US: (bi kôz′, -koz′, -kuz′)

WordReference Random House Learner's Dictionary of American English © 2026

be•cause /bɪˈkɔz, -ˈkʌz/   conj. 

1. for the reason that;
   due to the fact that:
   always late because it took so long to get dressed.

prep. 

2. Idioms because of, for the reason of;
   on account of;
   due to:
   The train was late because of the bad weather.

Usage

Use because before the reason or cause for something when there are two clauses you are joining; use because of when a noun phrase, not a clause, describes the reason for something.

WordReference Random House Unabridged Dictionary of American English © 2026

be•cause  (bi kôz′, -koz′, -kuz′), conj. 

1. for the reason that;
   due to the fact that:
   The boy was absent because he was ill.
2. Idioms because of, by reason of;
   due to:
   Schools were closed because of heavy snowfall.

• Middle English bi cause by cause 1275–1325

Synonyms

• 1. Because, as, since, for, inasmuch as agree in implying a reason for an occurrence or action.
  Because introduces a direct reason:
  I was sleeping because I was tired.
  As and since are so casual as to imply merely circumstances attendant on the main statement:
  As
  (or since) I was tired, I was sleeping. The reason, proof, or justification introduced by for is like an afterthought or a parenthetical statement:
  I was sleeping, for I was tired.
  Inasmuch as implies concession; the main statement is true in view of the circumstances introduced by this conjunction:
  Inasmuch as I was tired, it seemed best to sleep.

Usage

1. See reason. 

Collins Concise English Dictionary © HarperCollins Publishers::

because / bɪˈkɒz -ˈkəz/ conjunction

1. (subordinating) on account of the fact that; on account of being; since: because it's so cold we'll go home
2. because of ⇒ (preposition) on account of: I lost my job because of her

Etymology: 14th Century bi cause, from bi by + causeUSAGE
reason