1540s, from French insidieux "insidious" (15c.) or directly from Latin insidiosus "deceitful, cunning, artful, treacherous," from insidiae (plural) "plot, snare, ambush," from insidere "sit on, occupy," from in- "in" (from PIE root *en "in") + sedere "to sit," from PIE root *sed- (1) "to sit." Figurative, usually with a suggestion of lying in wait and the intent to entrap. Related: Insidiously; insidiousness.
1590s, "remaining in one place," from French sédentaire (16c.) and directly from Latin sedentarius "sitting, remaining in one place," from sedentem (nominative sedens), present participle of sedere "to sit; occupy an official seat, preside; sit still, remain; be fixed or settled," from PIE root *sed- (1) "to sit." Of persons, the sense "not in the habit of exercise" is recorded from 1660s.
mid-15c., Scottish, "postpone, defer," from French superceder "desist, delay, defer," from Latin supersedere literally "sit on top of;" also, with ablative, "stay clear of, abstain from, forbear, refrain from," from super "above" (see super-) + sedere "to sit," from PIE root *sed- (1) "to sit." Meaning "displace, replace" first recorded 1640s. Related: Superseded; superseding.
1540s, "matter which settles at the bottom of water or other liquid," from French sédiment (16c.) and directly from Latin sedimentum "a settling, sinking down," from stem of sedere "to settle, sit" (from PIE root *sed- (1) "to sit").
1530s, "different, at variance, disagreeing," from Latin dissidentem (nominative dissidens), present participle of dissidere "to be remote; disagree, be removed from," literally "to sit apart," from dis- "apart" (see dis-) + sedere "to sit," from PIE root *sed- (1) "to sit."
Meaning "dissenting, not conforming" is from 1837, originally in reference to an established church. Meaning "disagreeing in political matters" is by 1943.
late 15c., residen, "to remain at a place," from Old French resider (15c.) and directly from Latin residere "sit down, settle; remain behind, rest, linger; be left," from re- "back, again" (see re-) + sedere "to sit" (from PIE root *sed- (1) "to sit"). The meaning "to dwell permanently or for a considerable time" is attested by 1570s. Related: Resided; residing. Also from the French word are Dutch resideren, German residiren.
One job of the judge's assistant was to fix the amount of a fine or tax. Meaning "to estimate the value of property for the purpose of taxing it" is from 1809; transferred sense of "to judge the value of" (a person, idea, etc.) is from 1934. Related: Assessed; assessing.