Thank you, Faldage..
you know exactly how my mind works.. one one word (acute) is right there, for the grabbing and the other IS obtuse--and runs off and hides.

--like Acid--and its 'counterpart'..it's um, alcloid? no, its um, alcoloid? no that doesn't look right either.. how in heck am i suppose to find the word,(in a dictionary) when i don't have a clue-- the word slips out of my grasp like a bar of soap..
I know it when i see it.. but i can't see it in my mind's eye!--its a sort of blindness!