late 14c., darten, "to pierce with a dart" (a sense now obsolete), from dart (n.). Sense of "throw with a sudden thrust" is from 1570s. Intransitive meaning "to move swiftly" is from 1610s; that of "spring or start suddenly and run or move quickly" (like a dart) is from 1610s. Related: Darted; darter; darting.
early 15c., "capacity for motion, ability to move or be moved, property of being easily movable," from Old French mobilité "changeableness, inconsistency, fickleness" and directly from Latin mobilitatem (nominative mobilitas) "activity, speed," figuratively "changeableness, fickleness, inconstancy," from mobilis "movable, easy to move" (see mobile (adj.)). Socio-economics sense of "possibility of movement between different social levels" is from 1900 in sociology writing.
"raise or move by force," 1823, from a noun meaning "large lever used to raise or move heavy things, crowbar;" an alteration of prize (as though it were a plural) in its obsolete sense of "lever" (c. 1300), from Old French prise "a taking hold, grasp" (see prize (n.2)).