sed/sess/sid

sit; settle

Spelled sed, sess, sid · 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
as- (beside; form of ad-) + sid (sit) + -uous (having the quality of)
insidious — causing harm gradually or secretly
in- (in) + sid (sit) + -ious (having the quality of)
sedentary — involving much sitting and little physical activity
sed (sit) + -ent (doing) + -ary (relating to)
sediment — solid material that settles at the bottom of a liquid
sed (settle) + -ment (result)
session — a period devoted to a meeting or activity
sess (sit) + -ion (action or state)
preside — lead or be in charge of a meeting
pre- (before) + sid (sit)
subside — become less intense or sink to a lower level
sub- (down) + sid (settle)
resident — a person who lives in a particular place
re- (back) + sid (sit) + -ent (person who)

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.