verb (used without object), swore or (Archaic) sware; sworn; swear·ing.
verb (used with object), swore or (Archaic) sware; sworn; swear·ing.
- to name (a sacred being or thing) as one's witness or guarantee in swearing.
- Informal. to have great confidence in; rely on: He swears by his dentist.
- to have certain knowledge of: I thought I saw him leaving, but I couldn't swear by it.
Origin of swear
British Dictionary definitions for swear by
verb swears, swearing, swore or sworn
- to invoke (a deity, etc) by name as a witness or guarantee to an oath
- to trust implicitly; have complete confidence (in)
Word Origin for swear
Idioms and Phrases with swear by
Have great reliance on or confidence in, as in She swears by her personal physician. [Early 1800s]
Also, swear to. Have reliable knowledge of, be sure of, as in I think she was going to the library but I can't swear to it. [Mid-1700s]
Take an oath by, as in I swear by all the saints in heaven. [Early 1200s]