before vowels myel-, word-forming element meaning "marrow, spinal cord," from Greek myelos "marrow; the brain," a word of unknown origin.
before vowels morph-, word-forming element of Greek origin meaning "form, shape," from Greek morphē "form, shape; beauty, outward appearance," a word of uncertain etymology.
"shirt, chemise, body garment of linen or cotton for either sex," Middle English serk, late Old English serc "shirt, corselet, coat of mail," surviving as a Scottish and northern dialect word. It is either the Old English word influenced in pronunciation and spelling by its Old Norse cognate serkr, or that word in place of the native one. A general Germanic word (see shirt and also compare berserk.
word-forming element in medicine meaning "a vein or veins," from Greek phlebo-, combining form of phleps "vein," a word of uncertain origin.