harshly uninviting or formidable in manner or appearance; "a dour, self-sacrificing life"; "a forbidding scowl"; "a grim man loving duty more than humanity"; "undoubtedly the grimmest part of him was his iron claw"- J.M.Barrie
not changeable or subject to change; "a fixed and unchangeable part of the germ plasm"-Ashley Montagu; "the unchangeable seasons"; "one of the unchangeable facts of life"
precisely determined or limited or defined; especially fixed by rule or by a specific and constant cause; "a determinate distance"; "a determinate number"; "determinate variations in animals"
not continuing to grow indefinitely at the apex; "determinate growth"