Synonyms for Impressive:

adj.

all (adjective)
telling.
amazing (adjective)
amazing, astonishing, bewildering, astounding, surprising, awesome, dazzling, overwhelming.
ambitious (adjective)
formidable, grandiose, lofty.
astonishing (adjective)
astounding, bewildering, stunning, stupefying, amazing, spectacular, staggering.
august (adjective)
glorious, baronial, brilliant, magnificent.
authoritative (adjective)
commanding, authoritative, consequential, imperious, dictatorial, strong, important, authoritarian, arrogant, powerful, masterful, potent, effective, autocratic, influential, effectual.
awesome (adjective)
astonishing, awful, overwhelming.
believable (adjective)
convincing, persuasive.
commanding (adjective)
autocratic, dictatorial, imperious.
convincing (adjective)
powerful, telling.
impressive (adjective)
exciting, inspiring, profound, stirring, affecting, absorbing, towering, moving, momentous, consequential, striking, important, touching, grand, noble, arresting, notable, splendid, stately, massive, intense, remarkable, effective, penetrating, eloquent, thrilling, awe-inspiring, dramatic, imposing, extraordinary, rousing, majestic, vital.
large (adjective)
elephantine, princely, enormous, expansive, large, voluminous, immense, copious, grand, huge, baggy, majestic, bulky, extensive, vast, prodigious, spacious, towering, cavernous, great, colossal, giant, big, grandiose, soaring, massive, gargantuan, awesome, gigantic, ample, lofty, comprehensive, capacious, generous, magnificent, tremendous, humongous, mammoth, sizable, roomy.
noticeable (adjective)
arresting.
persuasive (adjective)
convincing.
surprising (adjective)
astonishing.
touching (adjective)
touching.

n.

high, king-size, wide. moving, stirring, poignant, touching, touch, affecting. impressive (noun)
dazzling, telling, stunning, spectacular, astonishing, important-looking, awesome, amazing, gallant, astounding, mind-boggling, awful, striking, arresting, majestic, stately, dramatic, staggering, formidable, awing, splendid, proud, imposing, effectual, signal, magnificent, expansive, palatial, awe-inspiring, grandiose, sensational, brilliant, effective, thundering, heroic, fulgurant, glorious, lofty, baronial, grand, stupefying, efficacious, fulgurous, noble.

Other synonyms:

poignant, stirring, touching, affecting, moving. formidable
formidable.
imposing
imposing.
persuasive
convincing.
stimulating
exciting.

Usage examples for impressive

  1. The meeting of the three was impressive for not only had they been much attached at the time of the preacher's former visit, but the women were deeply affected by the sad circumstances in which they found their old friend. – The Prairie Chief by R.M. Ballantyne
  2. In his own peculiar style he was impressive – Beyond by John Galsworthy
  3. Then followed an impressive silence. – Campaigning with Crook and Stories of Army Life by Charles King