Not quite an erection, but getting there.
When I saw Milla Jovovich's boobies I got a semi.
by Germ March 15, 2003
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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
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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 March 1, 2006
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1 -(n.) Any semi-automatic weapon; semi-shots, smg's, etc. (pronounced "seh-MEE")

2 -(n.) An 18-wheeler truck (pronounced "seh-MI")

1 - "Semi's are only half as fun as automatics."

2 - "Aparrently a semi loaded with cocaine and doritos rolled over on the freeway yesterday.
by Lil Dre March 19, 2006
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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 February 1, 2015
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Say "semeh" or "semi hot up" or "semi hot"
The primal meaning is when some situation is slightly conspicuous but not blatent. It comes from the word hot up which means conspicuous, originated in Tinsley, Sheffield. Pronoced in a northern british(yorkshire)accent.
Also the word is often used when a situation that should perhaps be subtle or secrative is really obvious, in which case it is used sarcastically, sometimes as "bare semi".
You've just picked up and ate a sweet from the pick and mix section in a store. You're friend says, "semi"

Two friends in a car at night jump a red light and then notice the car stopped oppisite is a police car. One of them says "semi", the other replies "bare semi".
by Harry Khan June 29, 2008
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yo when we go to tha club sure to pack a semi
by diizzii May 18, 2003
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