mid-14c., ponderen, "to estimate the worth of, to appraise" (a sense now obsolete), from Old French ponderer "to weigh, poise" (14c., Modern French pondérer) and directly from Latin ponderare "ponder, consider, reflect," literally "to weigh," from pondus (genitive ponderis) "weight," from stem of pendere "to hang, cause to hang; weigh" (from PIE root *(s)pen- "to draw, stretch, spin"). Meaning "to judge (a matter or action) mentally, weigh carefully in the mind" is attested from late 14c. Related: Pondered; pondering; ponderation (1550s in the mental sense).

"weight, gravity, importance," 1798, from ponder + -ance or Latin ponderantem. Ponderment as "the act of weighing (something) in the mind" is by 1763.

1794, "weightless," from assimilated form of in- (1) "not, opposite of" + ponderable (see ponder). Figurative use, "unthinkable," from 1814. As a noun from 1829, originally meaning heat, light, electricity, etc., as having no weight. Related: Imponderably; imponderability. Imponderous is attested from 1640s as "without weight." Imponderabilia "unthinkable things collectively" is attested from 1835.

Proto-Indo-European root meaning "to draw, stretch, spin."

It forms all or part of: append; appendix; avoirdupois; compendium; compensate; compensation; counterpoise; depend; dispense; equipoise; expend; expense; expensive; hydroponics; impend; painter (n.2) "rope or chain that holds an anchor to a ship's side;" pansy; penchant; pend; pendant; pendentive; pending; pendular; pendulous; pendulum; pension; pensive; penthouse; perpendicular; peso; poise; ponder; ponderous; pound (n.1) "measure of weight;" prepend; prepense; preponderate; propensity; recompense; span (n.1) "distance between two objects;" span (n.2) "two animals driven together;" spangle; spanner; spend; spider; spin; spindle; spinner; spinster; stipend; suspend; suspension.

It is the hypothetical source of/evidence for its existence is provided by: Latin pendere "to hang, to cause to hang," pondus "weight" (perhaps the notion is the weight of a thing measured by how much it stretches a cord), pensare "to weigh, consider;" Greek ponos "toil," ponein "to toil;" Lithuanian spendžiu, spęsti "lay a snare;" Old Church Slavonic peti "stretch, strain," pato "fetter," pina "I span;" Old English spinnan "to spin," spannan "to join, fasten; stretch, span;" Armenian henum "I weave;" Greek patos "garment," literally "that which is spun;" Lithuanian pinu "I plait, braid," spandau "I spin;" Middle Welsh cy-ffiniden "spider;" Old English spinnan "draw out and twist fibers into thread," spiðra "spider," literally "spinner."

"ponder, consider," 1560s, from pre- "before" + Latin pendere "to hang, cause to hang; weigh; pay" (from PIE root *(s)pen- "to draw, stretch, spin"). Related: Prepended; prepending.

"to reflect, ponder, meditate; to be absorbed in thought," mid-14c., from Old French muser (12c.) "to ponder, dream, wonder; loiter, waste time," which is of uncertain origin; the explanation in Diez and Skeat is literally "to stand with one's nose in the air" (or, possibly, "to sniff about" like a dog who has lost the scent), from muse "muzzle," from Gallo-Roman *musa "snout," itself a word of unknown origin. The modern word probably has been influenced in sense by muse (n.). Related: Mused; musing.

reflexive verb, Middle English bithinken, "think, meditate, reflect, ponder," from Old English beþencan "to consider, remember, take thought for, reflect," from be- + þencan "to think" (see think). Related: Bethought.

late 14c., "action of testing or judging; judicial inquiry," from Old French examinacion, from Latin examinationem (nominative examinatio), noun of action from past-participle stem of examinare "to weigh; to ponder, consider" (see examine). Sense of "test of knowledge" is attested from 1610s.

"capable of being compensated," 1660s, from French compensable (16c.), from compenser, from Latin compensare (see compensate). Middle English had the simple verb compense "make up for (something), counterbalance, compensate; requite; satisfy (a need)," from Latin compensus, but compensate seems to have replaced it. The Old French adjective compensable meant "to consider, ponder."

1580s, "to ponder, think abstractly, engage in mental contemplation" (intransitive), probably a back-formation from meditation, or else from Latin meditatus, past participle of meditari "to meditate, think over, reflect, consider," frequentative form of PIE root *med- "take appropriate measures." From 1590s as "to plan in the mind," also "to employ the mind in thought or contemplation," especially in a religious way. Related: Meditated; meditating.