Words...

Pertinent... Pertinacious... you'd think they would have a vaguely similar meaning, wouldn't you?

per·ti·nent (pûr'tn-ənt)
adj.

Having logical precise relevance to the matter at hand. See synonyms at relevant.

[Middle English, from Old French partenant, pertinent, from Latin pertinēns, pertinent-, present participle of pertinēre, to pertain. See pertain.]

per·ti·na·cious (pûr'tn-ā'shəs)
adj.

1. Holding tenaciously to a purpose, belief, opinion, or course of action.
2. Stubbornly or perversely persistent. See synonyms at obstinate.

[From Latin pertināx, pertināc- : per-, per- + tenāx, tenacious (from tenēre, to hold).]

Typically though, I think they're functional opposites - the more someone insists on sticking to a point, the less relevant it usually is.

Don't you just hate the kind of people who will go on and on about why that's not a square peg - it's rectangular, or cuboid or something - when in actual fact, no-one cares about the square peg, because the hole we have is round!

Tuesdays suck.