Top Definition
Not quite an erection, but getting there.
When I saw Milla Jovovich's boobies I got a semi.
by Germ March 15, 2003
the in-between state of a limp dick and a usable hard-on. can be on the way to hard, on the way back from hard, or never allowed to get more than 60% (+/-) hard.
many a young man learn to hide their semi with text books after day-dreaming in class
by the mac al February 28, 2006
the state of a penis which is not altogether flaccid nor erect. It will often occur at inopportune embarrasing times and will be brought on purposefully by a cunning sexy woman pretending she has no idea what she is doing.
"why are you still friends with some of your ex-boyfriends?"

"I like to keep them healthy and providing the regular semi keeps the circulatory system in check."
by MintyLeila June 18, 2005
The word that comes up on t9 phones when the word "penis" is intended to be typed.
I got a text from Benjy that says, "I put my semis in her butt."
by Danielwritesstuff January 14, 2009
A person who has a high tolerance, or can take numerous shots, blows, etc, but remains stoic or unfazed. The usual context is referring to a person in a fight or a person drinking numerous shots.
He's not even fazed. We got ourselves a full-blown semi.
by The Great Dark January 31, 2015
A small boner over something none sexually related. It will be about 50% smaller
100% on a maths test forced him to get a semi
by Ben Ski Don May 03, 2010
Semi's is semi losers... Like semi's and full blown
Now we cross the line from semi's to full blown

I hate those fuckin semi's

by Allan S November 21, 2005

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