From the base of posis with enclitic adverb of origin; from which (as interrogative) or what (as relative) place, state, source or cause -- whence.
see GREEK posis
a. of place,from what place: Matthew 15:33; Luke 13:25, 27; John 3:8; John 6:5; John 8:14; John 9:29, 30; John 19:9; Revelation 7:13; from what condition, Revelation 2:5.
b. of origin or source, equivalent to from what author or giver: Matt. 13:( c. of cause, how is it that? how can it be that? Mark 8:4; Mark 12:37; Luke 1:43; John 1:48 (