suggestion n.

word-forming element meaning "under, beneath; behind; from under; resulting from further division," from Latin preposition sub "under, below, beneath, at the foot of," also "close to, up to, towards;" of time, "within, during;" figuratively "subject to, in the power of;" also "a little, somewhat" (as in sub-horridus "somewhat rough"), from PIE *(s)up- (perhaps representing *ex-upo-), a variant form of the root *upo "under," also "up from under." The Latin word also was used as a prefix and in various combinations.

In Latin assimilated to following -c-, -f-, -g-, -p-, and often -r- and -m-. In Old French the prefix appears in the full Latin form only "in learned adoptions of old Latin compounds" [OED], and in popular use it was represented by sous-, sou-; as in French souvenir from Latin subvenire, souscrire (Old French souzescrire) from subscribere, etc.

The original meaning is now obscured in many words from Latin (suggest, suspect, subject, etc.). The prefix is active in Modern English, sometimes meaning "subordinate" (as in subcontractor); "inferior" (17c., as in subhuman); "smaller" (18c.); "a part or division of" (c. 1800, as in subcontinent).

"famous deed, exploit," more commonly "story of great deeds, tale of adventure," c. 1300, from Old French geste, jeste "action, exploit, romance, history" (of celebrated people or actions), from Medieval Latin gesta "actions, exploits, deeds, achievements," noun use of neuter plural of Latin gestus, past participle of gerere "to carry on, wage, perform," which de Vaan says is considered to be from the same root as agere "to set in motion, drive forward, do, perform" (from PIE root *ag- "to drive, draw out or forth, move"). Now only as a deliberate archaism. Jest (n.) is the same word, with a decayed sense.