1) Changeless 2) Consistent 3) Constant 4) Fixed-income 5) Invariant 6) Not variable 7) Static or constant 8) Steady 9) Strict 10) Unvarying 1) Consistent 2) Constant 3) Fixed 4) Invariant 5) Stable 6) Steady 7) Strict 8) Unvariable 9) Unvarying 
• (n.) An invariable quantity; a constant. • (a.) Not given to variation or change; unalterable; unchangeable; always uniform.
In·va'ri·a·ble adjective [ Prefix in- not + variable : confer French invariable .] Not given to variation or change; unalterable; unchangeable; always uniform. « Physical laws which are invariable .» I. Taylor. -- In*va'ri*a*ble*ness , 
[adj] - not liable to or capable of change
adjective not liable to or capable of change; `an invariable temperature`; `an invariable rule`; `his invariable courtesy`
not variable; not changing or capable of being changed; static or constant.