"energetic force; motive force," 1894, from dynamic (adj.). As "manner of interaction," by 1978.
"given to speaking freely, candid, free or bold of speech," 1808, originally Scottish, from out- + -spoken. According to OED, the past participle "has here a resultant force, as in 'well spoken', 'well read'." Related: Outspokenly; outspokenness. Earlier was outspeaking, in reference to the voice, "loud, resonant" (mid-15c.).
"beat or play time on, or announce by beating on, a drum," 1570s, from drum (n.). Meaning "to beat rhythmically or regularly" (with the fingers, etc.) is from 1580s. Meaning "force upon the attention by continual iteration" is by 1820. To drum (up) business, etc., is American English 1839, from the old way of drawing a crowd or attracting recruits. To drum (someone) out "expel formally and march out by the beat of a drum" is originally military, by 1766.
"to compel, force," c. 1400, from Latin coactare "constrain, force," frequentative of cogere (past participle coactus) "to compel," also "curdle, collect" (see cogent). Related: Coacted; coacting; coaction; coactive.