The Collaborative International Dictionary of English v.0.48:

Unfaltering \Unfaltering\
   See faltering.

WordNet (r) 3.0 (2006):

unfaltering
    adj 1: marked by firm determination or resolution; not shakable;
           "firm convictions"; "a firm mouth"; "steadfast resolve";
           "a man of unbendable perseverence"; "unwavering loyalty"
           [syn: firm, steadfast, steady, stiff,
           unbendable, unfaltering, unshakable, unwavering]

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "unfaltering":
   abiding, arrogant, assiduous, assured, calm, cocksure, confident,
   constant, continuing, convinced, coolheaded, decided, determined,
   diligent, dogged, enduring, faithful, firm, hubristic, immutable,
   inalterable, indefatigable, indomitable, industrious, inexcitable,
   insistent, invincible, lasting, loyal, nerveless, never-failing,
   never-tiring, obstinate, overconfident, oversure, overweening,
   patient, patient as Job, permanent, perseverant, persevering,
   persistent, persisting, persuaded, pertinacious, plodding,
   plugging, poised, pompous, positive, preoccupied, proud, rapt,
   reassured, relaxed, relentless, resolute, rock-steady, secure,
   sedulous, self-assured, self-confident, self-important,
   self-reliant, single-minded, sleepless, slogging, stable,
   steadfast, steady, steady-handed, steady-nerved, steel-nerved,
   stick-at-nothing, strong-nerved, stubborn, sure, tenacious,
   tireless, unabating, unafraid, unblenching, unblinking,
   unconquerable, undaunted, undiscouraged, undoubting, undrooping,
   unfailing, unflagging, unflinching, unhesitant, unhesitating,
   unintermitting, uninterrupted, unnervous, unnodding, unqualified,
   unquestioning, unquivering, unrelaxing, unrelenting, unremitting,
   unshaken, unshaky, unshrinking, unsleeping, unstrained, unswerving,
   untiring, untremulous, unwavering, unwearied, unwearying,
   unwinking, utterly attentive, weariless, wholehearted,
   without a tremor