gravimeter (n.)

c. 1500, "weight, dignity, seriousness, solemnity of deportment or character, importance," from Old French gravité "seriousness, thoughtfulness" (13c.) and directly from Latin gravitatem (nominative gravitas) "weight, heaviness, pressure," from gravis "heavy" (from PIE root *gwere- (1) "heavy"). The scientific sense of "downward acceleration of terrestrial bodies due to gravitation of the Earth" first recorded 1620s.

The words gravity and gravitation have been more or less confounded; but the most careful writers use gravitation for the attracting force, and gravity for the terrestrial phenomenon of weight or downward acceleration which has for its two components the gravitation and the centrifugal force. [Century Dictionary, 1902]

word-forming element meaning "device or instrument for measuring;" commonly -ometer, occasionally -imeter; from French -mètre, from Greek metron "a measure," from PIE root *me- (2) "to measure."

gwerə-, Proto-Indo-European root meaning "heavy."

It forms all or part of: aggravate; aggravation; aggrieve; bar (n.4) "unit of pressure;" bariatric; baritone; barium; barometer; blitzkrieg; brig; brigade; brigand; brigantine; brio; brut; brute; charivari; gravamen; grave (adj.); gravid; gravimeter; gravitate; gravity; grief; grieve; kriegspiel; guru; hyperbaric; isobar; quern; sitzkrieg.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit guruh "heavy, weighty, venerable;" Greek baros "weight," barys "heavy in weight," often with the notion of "strength, force;" Latin gravis, "heavy, ponderous, burdensome, loaded; pregnant;" Old English cweorn "quern;" Gothic kaurus "heavy;" Lettish gruts "heavy."