Nouns

(n)sitting, posing(photography) the act of assuming a certain position (as for a photograph or portrait)“he wanted his portrait painted but couldn't spare time for the sitting”
(n)sittingthe act of assuming or maintaining a seated position“he read the mystery at one sitting”
(n)seance, sitting, sessiona meeting of spiritualists“the seance was held in the medium's parlor”
(n)sittinga session as of a legislature or court

Adjectives

(a)seated, sitting(of persons) having the torso erect and legs bent with the body supported on the buttocks“the seated Madonna”, “the audience remained seated”
(s)sittingnot moving and therefore easy to attack“a sitting target”