sed/sess/sid

sit; settle

Spelled sed, sess, sid · Latin sedere 'sit', with forms sed-, sess-, and sid-

Latin sedere meant 'sit': sedentary people sit, sediment settles, and an insidious enemy sits in wait.

Words built from it

assiduous — working with steady care and effort
ad- (at, beside) + sedere (sit) → Latin assidere (sit beside) → assiduus (constantly present) → assiduous
insidious — causing harm gradually or secretly
in- (in) + sedere (sit) → Latin insidere (sit in) → insidiae (ambush) → insidiosus (treacherous)
sedentary — involving much sitting and little physical activity
Latin sedere (sit) → sedent- (sitting) + -arius (relating to) → sedentarius
sediment — solid material that settles at the bottom of a liquid
Latin sedere (sit, settle) + -mentum (result) → sedimentum (a settling)
session — a period devoted to a meeting or activity
Latin sedere (sit) → sess- + -ion (action or state) → sessio (a sitting)
preside — lead or be in charge of a meeting
prae- (before) + sedere (sit) → Latin praesidere (sit before, supervise)
subside — become less intense or sink to a lower level
sub- (down, under) + sedere (sit) → Latin subsidere (sit down, sink)
resident — a person who lives in a particular place
re- (back) + sedere (sit) → Latin residere (sit back, remain) → resident- (remaining)

seditious — From Latin seditio, 'rebellion': se- (apart) + itio (a going), from ire (go). Its sed does not mean 'sit'.

-ary/-ory — Makes adjectives meaning relating to, or nouns for associated people, things, or places.