cis-

Proto-Indo-European root, the stem of demonstrative pronoun meaning "this."

It forms all or part of: cis-; et cetera; harass; he; hence; her; here; him; his; hither; it.

It is the hypothetical source of/evidence for its existence is provided by:  Greek ekeinos "that person;" Latin cis "on this side," citra (adv.) "on this side;" Old Church Slavonic si, Lithuanian is, Hittite ki "this;" Old English hider, Gothic hidre "hither."

word-forming element meaning "across, beyond, through, on the other side of, to go beyond," from Latin trans (prep.) "across, over, beyond," perhaps originally present participle of a verb *trare-, meaning "to cross," from PIE *tra-, variant of root *tere- (2) "cross over, pass through, overcome." In chemical use indicating "a compound in which two characteristic groups are situated on opposite sides of an axis of a molecule" [Flood].