Strong's Definition
(by implication) very widely used as a relative conjunction or adverb (as below); often largely modified by other particles annexed
Derivation: a primitive particle (the full form of the prepositional prefix) indicating causal relations of all kinds, antecedent or consequent;
KJV Usage: and, + (forasmuch, inasmuch, where-) as, assured(-ly), + but, certainly, doubtless, + else, even, + except, for, how, (because, in, so, than) that, + nevertheless, now, rightly, seeing, since, surely, then, therefore, + (al-) though, + till, truly, + until, when, whether, while, whom, yea, yet.
TWOT Reference: 976
Outline of Biblical Usage
1) that, for, because, when, as though, as, because that, but, then, certainly, except, surely, since
1a) that
1a1) yea, indeed
1b) when (of time)
1b1) when, if, though (with a concessive force)
1c) because, since (causal connection)
1d) but (after negative)
1e) that if, for if, indeed if, for though, but if
1f) but rather, but
1g) except that
1h) only, nevertheless
1i) surely
1j) that is
1k) but if
1l) for though
1m) forasmuch as, for therefore
Brown-Driver-Briggs Hebrew Lexicon
כִּי
ký̂y
BDB Definition:
1) that, for, because, when, as though, as, because that, but, then, certainly, except, surely, since
1a) that
1a1) yea, indeed
1b) when (of time)
1b1) when, if, though (with a concessive force)
1c) because, since (causal connection)
1d) but (after negative)
1e) that if, for if, indeed if, for though, but if
1f) but rather, but
1g) except that
1h) only, nevertheless
1i) surely
1j) that is
1k) but if
1l) for though
1m) forasmuch as, for therefore
Part of Speech: conjunction
A Related Word by BDB/Strongs Number: a primitive particle
Same Word by TWOT Number: 976
Total KJV Occurrences: 1120