Synonyms for Irrelevance:

n.

immaterial, extraneous, beside the point, marginal, unimportant, inappropriate, irrelevant, unrelated, neither here nor there, academic. stuff, adjunct, Minutiae, dead wood, nothing, inessentials, non-issue, detail. alienation (noun)
difference, remoteness, foreignness, disjunction, other, alienation, dissociation, detachment, extraneousness, division, breach, separation, inapplicability, segregation.
extraneousness (noun)
impertinence, disconnection, strangeness, disaffiliation, inappropriateness, inadmissibility, outlandishness.
irrelevance (noun)
inappositeness, incongruity, insignificance, inapplicability, irrelevancy, unrelatedness, inappropriateness, immateriality, triviality, impertinence, inconsistency, remoteness.
irrelevancy (noun)
inappositeness, immateriality, unrelatedness, lack of connection, inconsistency, incongruity, triviality.
linkdef (noun)
irrelevancy.
negligibility (noun)
inconsequence, unimportance.
unimportance (noun)
inconsequence, frivolity, unimportance, minutia, triteness, insignificance, insipidity, trivia, triflingness, banality.

Other synonyms:

nothing, inessentials, Minutiae, dead wood, non-issue. detail, adjunct, stuff. Other relevant words:
irrelevant, academic, unrelatedness, incongruity, detail, stuff, adjunct, unimportant, inconsistency, non-issue, nothing, marginal, immaterial, Minutiae, triviality, inessentials, inappositeness, extraneous, irrelevancy, inappropriate, immateriality, unrelated.