A is irrelevant to B “or” or “nor” C?

Question

If I want to convey A is irrelevant to B, and A is irrelevant to C. Should I say:

A is irrelevant to B or C.

Or

A is irrelevant to B nor C.

Or any other expressions?

Answer 1

Generally speaking, you need a separate "negative polarity" element in your sentence (or your multi-sentence thought) to trigger the use of nor. These would be words such as No, not, never, nothing, or neither; a negating prefix like ir-, non- or de- is not enough to make a nor show up in standard use.

So you could say

A is irrelevant to either B or C

A is irrelevant to B and to C

A is relevant to neither B nor C

A is not relevant to B nor C

Nothing in A is relevant to B; nor is it relevant to C.

There is no relevance between A and B, nor between A and C

Some "high-formality" uses of nor by itself intend for the neither to be implied:

A is relevant to B nor C == "A is relevant to neither B nor C"

But this is an uncommon construction these days and should probably be avoided, as many people will construe it to be an error.

Answer 2

This question can be answered logically.

A is irrelevant to B and C.

or (more awkwardly):

A is relevant to neither B nor C.