Synonyms and related words :
assiduous, balanced, calm, constant, continuing, cool, coolheaded, diligent, dogged, enduring, faithful, fast, fiducial, firm, firm as Gibraltar, immutable, imperturbable, implacable, in equilibrium, inalterable, indefatigable, indomitable, industrious, inexcitable, insistent, invincible, lasting, loyal, merciless, mortal, nerveless, never-tiring, obstinate, patient, patient as Job, permanent, perseverant, persevering, persistent, persisting, pertinacious, plodding, plugging, predictable, preoccupied, rapt, relaxed, relentless, reliable, resolute, rock-steady, ruthless, secure, sedulous, single-minded, sleepless, slogging, solid, sound, stable, steadfast, steady, steady-handed, steady-nerved, steel-nerved, stick-at-nothing, strong-nerved, stubborn, substantial, tenacious, tireless, unabashed, unabating, unappalled, unappeasable, unawed, unblenching, unblinking, unconquerable, uncowed, uncringing, undaunted, undiscouraged, undismayed, undrooping, unfailing, unfaltering, unflagging, unflappable, unhesitant, unhesitating, unintermitting, uninterrupted, unintimidated, unnervous, unnodding, unquivering, unrelaxing, unrelenting, unremitting, unshakable, unshaken, unshaky, unshrinking, unsleeping, unstrained, unswerving, untiring, untremulous, unwavering, unwearied, unwearying, unwinking, unyielding, utterly attentive, weariless, well-balanced, without a tremor, without nerves