Synonyms for Irrelevant:

adj.

beside the point (adjective)
not to the purpose, beside the question.
dull (adjective)
pointless.
extraneous (adjective)
inadmissible, foreign-born, disaffiliated, immaterial, estranged, dissociated, eerie, unrelated, alien, unaffiliated, removed, extrinsic, disconnected, outlandish, disjoint, separated, extraneous, external, unessential, Unallied, outside, inappropriate, parenthetical, other, extraterrestrial, detached, exotic, segregated, outer, impertinent, strange, foreign, inapplicable, nonessential, separate.
idle (adjective)
frivolous.
ill-suited (adjective)
unsuitable.
insignificant (adjective)
nonessential, trifling, minute.
irrelevant (adjective)
off the point, inconsequential, inapplicable, out of order, remote, unrelated, not germane, off the topic, unnecessary, foreign, trivial, extraneous, inappropriate, impertinent, inconsequent, outside, immaterial, not connected with, not pertaining to, unimportant, insignificant, out of place, pointless.
obscure (adjective)
removed.
unimportant (adjective)
minute, trivial, insignificant, fiddling, piddling, measly, worthless, trite, insipid, one-horse, banal, inconsequential, trifling, Flyspeck, unimportant, frivolous.
unnecessary (adjective)
unessential.
unrelated (adjective)
detached, separate, alien, unrelated, not germane, unaffiliated, disjoint, dissociated, remote, foreign, Unallied, extraneous, segregated, disenfranchised, inapplicable.

adv

unimportant (adverb)
neither here nor there.

n.

marginal, academic. inapplicable (noun)
beside the question, off the topic, inconsequent, neither here nor there, not to the purpose, beside the point, pointless, without reference to, out-of-the-way, not pertaining to, unnecessary, inapropros, out of order, not germane, off the point, out of place, not connected with.
irrelevant (noun)
extraneous, unsuitable, inapplicable, impertinent, digressive, immaterial, tangential.

Other synonyms:

marginal. academic. needless
unnecessary.
Other relevant words:
unnecessary, beside the question, inapropros, out of place, not germane, beside the point, digressive, tangential, inconsequent, not pertaining to, off the topic, pointless, not connected with, neither here nor there, unsuitable, academic, out-of-the-way, out of order, off the point, marginal.

Usage examples for irrelevant

  1. Brasher had impatiently waited for this, to him unimportant and irrelevant matter to be disposed of. – Death Points a Finger by Will Levinrew