therefore

adverb

1. in consequence of that; as a result; consequently: I think; therefore I am.

sentence connector

1. thus; hence: used to mark an inference on the speaker’s partthose people have their umbrellas up: therefore, it must be raining
2. consequently; as a resultthey heard the warning on the radio and therefore took another route

adv.Old English þærfore; from there + fore, Old English and Middle English collateral form of for. Since c.1800, therefor has been used in sense of “for that, by reason of that;” and therefore in sense of “in consequence of that.”