Muninonymous (mew-knee-non-o-muss), adj.

1.) Feeling of separation from fellow public transportation users either by choice or by circumstance.
2.) A rider who willfully avoids eye contact with other passengers for purposes of avoiding unwanted social engagement.
3.) Awkward, recurring eye contact with an acquaintance without confirmation or conversation.

Examples:

— I saw x on the train this morning but felt it better to ride muninonymously rather than feel like an ass when x turned out to be not who I thought x was.

— Even though I ride the N-Judah everyday, I still feel completely muninonymous here – you’d think I’d see some of the same people, but I never seem to.