histidine (n.)

medical word-forming element, from Greek histos "warp, web," literally "anything set upright," from histasthai "to stand," from PIE root *sta- "to stand, make or be firm." Taken by 19c. medical writers as the best Greek root from which to form terminology for "tissue, structural element of the animal body."

word-forming element used in chemistry to coin names for simple compounds of one element with another element or radical; originally abstracted from oxide, which was the first so classified, in which the -ide is from acide "acid."

The suffix is really -dus (-do-), the -i- repr. the orig. or supplied stem-vowel ; it occurs without the vowel in absurdus, absurd, blandus, bland, crudus, raw (crude), etc. [Century Dictionary]