"from a higher to a lower place, state, or condition," late 12c., from down (adv.) + -ward. As a preposition, "down," by late 14c. As an adjective, "moving or tending from a higher to a lwer place, state, or condition," from 1550s. As an adverb Old English had aduneweard. Downwards (c. 1200), with adverbial genitive, had a parallel in Old English ofduneweardes.
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.
1983, popularized 1991 in Persian Gulf War military slang, rough acronym for high-mobility multipurpose wheeled vehicle.
common popular designation of metallic mercury, Middle English quik-silver, from late Old English cwicseolfor, literally "living silver," so called for its mobility, translating Latin argentum vivum (source also of Italian argento vivo), "living silver;" so called from its liquid mobility. See quick (adj.) + silver (n.). Similar formation in Dutch kwikzilver, Old High German quecsilbar, German quecksilber, French vif-argent, Italian argenta viva.
"short, quick, forward and downward motion of the head," voluntary or not, 1530s, from nod (v.).
1710, "a downward movement," from down (adv.). Football sense of "an attempt to advance the ball" is by 1882.