Help with a word: its driving me nuts!!!!

[theotherranch]

Ad lib? I know,no "c" but it works.

 

[WooingWyandotte]

Quote:
Why do you need the word?

 

[mamabigbird]

Quote:
I don't care if it isn't the one ... I love that word! It feels good to say it.
Perspicacity ... perspicacity ... perspicacity!