glycolysis (n.)

before vowels glyc-, word-forming element meaning "sweet," from Latinized combining form of Greek glykys, glykeros "sweet" (see gluco-). Used in reference to sugars generally. OED says a regular formation would be glycy-.

scientific/medical word-forming element meaning "loosening, dissolving, dissolution," from Greek lysis "a loosening, setting free, releasing; dissolution; means of letting loose," from lyein "to unfasten, loose, loosen, untie," from PIE root *leu- "to loosen, divide, cut apart."