Is a phrasal verb:

1. Pin down sth: Understand accurately sth;
1. We do have to PIN DOWN the math topics.
by Érico February 5, 2012
To be trapped in some place
"That fucking sniper got me pinned down behind this wall"
by oroddkw September 21, 2009
Being cornered by a co-worker, with no obvious means of escape, and having to listen endlessly to boring stories. The urgency of the situation is proportional to the story - listening to Star Trek or boob job stories requires immediate intervention.
Quick, Alan's pinned down by the water cooler! Page him!
by Marc Bernard March 13, 2006
To engage in a friendly, playful round of Greco-Roman Wrestling with your Grandfather during which you are pinned to the floor, inadvertently fondled and able to feel his erect penis poking you. Typically result in an immediately yelling of "I give" and no further discussion or wrestling ensues.
Dan: Hey Carl. Want to take a ride with me? I need to run this assisted living brochure over to my Grandpa's house.
Carl: No thanks Braaaaahhhh. I still am scarred from the last time I went with you there. Not this time. No way I am getting the Silver Pin Down again brooooohhh!!
Dan: Oh come one brother!! I can't wrestle him by myself. It's too awkward when Grandma's gone.
by Eaton Holgoode May 18, 2015
the act of taking off someone's glasses while they're asleep, pooping across the bridge of the nose and pushing the glasses down until they're stuck to the face of the person sleeping.
last night Dru fell asleep geared up with his glasses on so i decided to portugese pin-down him since he waffle pressed my computer
by y'allz daddy June 9, 2010
Define or identify something precisely.
Dammit.I can't pin it down.It's too dark.
by BlackPohatu September 1, 2016