before vowels mer-, word-forming element meaning "part, partial, fraction," from Greek meros "a part, a fraction," from PIE root *(s)mer- (2) "to get a share of something."
word-forming element meaning "eating," from Greek phago- "eating, devouring," from PIE root *bhag- "to share out, apportion; to get a share." As in Phagiphany, the name of the Church festival celebrating the miracle of the fishes and loaves.
word-forming element meaning usually "one half more" than the indicated unit, from Latin sesqui-, sesque- "one and a half; one-half more," contraction of *semis-que- "a half in addition," from *semis "a half" (see semi-) + -que "and" (from PIE root *kwe "and, -ever," for which see ubiquity). Latin semi- had a tendency to get partly swallowed in compounds; compare these derivatives listed in de Vaan: selibra "half a libra," semodius "half a modius," sestertius "having the value of two-and-a-half" (as a noun, the name of a silver Roman coin, short for sestertius nummus), contracted from *semistertius; simbella "coin worth half a libella;" sincipitis "a half-head."
word-forming element meaning "disease," from Greek nosos "disease, sickness, malady," a word of unknown origin.
before vowels bronch-, word-forming element meaning "bronchus," from Latinized form of Greek bronkhos "windpipe," a word of unknown origin.
before vowels log-, word-forming element meaning "speech, word," also "reason," from Greek logos "word, discourse; reason," from PIE root *leg- (1) "to collect, gather," with derivatives meaning "to speak (to 'pick out words')."
because g- followed by some vowels in English usually has a "soft" pronunciation, a silent -u- sometimes was inserted between the g- and the vowel in Middle English to signal hardness, especially in words from French; but this was not done with many Scandinavian words where hard "g" precedes a vowel (gear, get, give, etc.). Germanic -w- generally became -gu- in words borrowed into Romance languages, but Old North French preserved the Frankish -w-, and English sometimes borrowed both forms, hence guarantee/warranty, guard/ward, etc.
before vowels myel-, word-forming element meaning "marrow, spinal cord," from Greek myelos "marrow; the brain," a word of unknown origin.
word-forming element in medicine meaning "a vein or veins," from Greek phlebo-, combining form of phleps "vein," a word of uncertain 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.