(s)rigid, stiffincapable of or resistant to bending“a rigid strip of metal”, “a table made of rigid plastic”, “a palace guardsman stiff as a poker”, “stiff hair”, “a stiff neck”
(s)inflexible, rigid, unbendingincapable of adapting or changing to meet circumstances“a rigid disciplinarian”, “an inflexible law”, “an unbending will to dominate”
(s)fixed, set, rigidfixed and unmoving“with eyes set in a fixed glassy stare”, “his bearded face already has a set hollow look” (Connor Cruise O'Brien), “a face rigid with pain”