WordNet sense 1 (a person loved by another person):

sweetheart, truelove

WordNet sense 2 (certain not to fail):

sure

WordNet sense 3 (not showing abrupt variations):

level, unwavering

WordNet sense 4 ((of especially a person's physical features) not shaking or trembling):

firm

WordNet sense 5 (occurring at fixed intervals):

even, regular

WordNet sense 6 (consistent in performance or behavior):

dependable

WordNet sense 7 (not liable to fluctuate or especially to fall):

unfluctuating

WordNet sense 8 (resistant to change of position or condition):

stable

WordNet sense 9 (marked by firm determination or resolution; not shakable):

steadfast, stiff, unfaltering, unshakable, unbendable

WordNet sense 10 (firm in purpose or belief; characterized by firmness and determination):

resolute

WordNet sense 11 (support or hold steady and make steadfast, with or as if with a brace):

brace, stabilize, stabilise

WordNet sense 12 (coming at short intervals or habitually):

frequent, frequent

WordNet sense 13 (not easily excited):

unexcitable

WordNet sense 14 (make steady):

becalm, calm

WordNet sense 15 (in a steady manner):

steadily