RIGID

[adjective] - stiff or fixed; not able to be bent, moved, changed or persuadeda rigid structurea rigid frameI was rigid with (= stiff and unable to move because of) pain/fear/etc.When I was studying for exams, I kept to a rigid routine/schedule.(disapproving) We were disappointed that they insisted on such a rigid interpretation of the rules.(disapproving) He lives by his own severe and rigid principles.