The Collaborative International Dictionary
Holo-
Holo- \Hol"o-\ A combining form fr. Gr. "o`los whole.
Douglas Harper's Etymology Dictionary
holo-
before vowels, hol-, word-forming element meaning "whole, entire, complete," from Greek holo-, comb. form of holos "whole, entire, complete," also "safe and sound," from PIE *sol-wo-, from root *sol- (see safe (adj.)).
Wiktionary
holo-
pre. 1 whole 2 hologram