through (prep., adv.)

late 14c., metathesis of Old English þurh, from Proto-Germanic *thurx (source also of Old Saxon thuru, Old Frisian thruch, Middle Dutch dore, Dutch door, Old High German thuruh, German durch, Gothic þairh "through"), from PIE root *tere- (2) "to cross over, pass through, overcome." Not clearly differentiated from thorough until early Modern English. Spelling thro was common 15c.-18c. Reformed spelling thru (1839) is mainly American English.

updated on August 16, 2018

Definitions of through from WordNet
through (adv.)
from beginning to end;
read this book through
through (adv.)
over the whole distance;
this bus goes through to New York
through (adv.)
to completion;
think this through very carefully!
through (adv.)
in diameter;
this cylinder measures 15 inches through
through (adv.)
throughout the entire extent;
I'm frozen through
knew him through and through
got soaked through in the rain
boards rotten through and through
a letter shot through with the writer's personality
Synonyms: through and through
through (adj.)
having finished or arrived at completion;
after the treatment, the patient is through except for follow-up
almost through with his studies
Synonyms: done / through with
through (adj.)
(of a route or journey etc.) continuing without requiring stops or changes;
a through bus
through traffic
a through street
Etymologies are not definitions. From, not affiliated with etymonline.