before vowels pyel-, medical word-forming element used from mid-19c. in forming medical terms, from Greek pyelos "oblong trough, bathing-tub," a word of uncertain etymology, taken in modern scientific use for "pelvis."
word-forming element in pathology meaning "condition of the blood," Modern Latin combining form of Greek haima (genitive haimatos) "blood," a word of no established etymology (replacing the usual IE word, represented in Greek by ear; possibly from uncertain PIE root *sei- "to drip" (compare Old High German seim "virgin honey," Welsh hufen), but according to Beekes this proposal "cannot explain the Greek vocalism."
word-forming element meaning "height," from Greek hypsos "height, top," from PIE *upso-, from root *upo "under," also "up from under," hence also "over" The Greek word is cognate with Sanskrit os "above, over," Old Church Slavonic vysoku "high."
before vowels chrys-, word-forming element meaning "gold, gold-colored," also sometimes "wealth," from Latinized form of Greek khrysos "gold," which is usually said to be a Punic (Semitic) loan-word (compare Hebrew and Phoenician harutz "gold").
also rhachio-, before vowels rachi-, word-forming element meaning "spinal, pertaining to the vertebrae," from Latinized form of Greek rhakhis "spine, back," metaphorically "ridge (of a mountain), rib of a leaf," a word of uncertain origin. Compare Greek rhakhos "thorn hedge."
before vowels thalass-, word-forming element meaning "sea, the sea," from Greek thalassa "the sea" (in Homer, when used of a particular sea, "the Mediterranean," as opposed to ōkeanos), a word from the Pre-Greek substrate language. In Attic Greek thalatta, hence sometimes thalatto-.