1. verb To make a big mistake or blunder; to mishandle or ruin something. I'm sorry, I really screwed up. Please forgive me! Wow, it looks like they really screwed up this time.

2. verb To ruin, damage, or mishandle something, especially inadvertently. In this usage, a noun or pronoun can be used between "screw" and "up." I can't believe you screwed that deal up! I screwed up my computer somehow—could you come take a look at it?

3. verb To damage or confuse someone's emotional or mental state. In this usage, a noun or pronoun can be used between "screw" and "up." Living with abusive parents really screwed him up. The divorce screwed me up for a long time.

4. verb To interfere with someone or their ability to do something. In this usage, a noun or pronoun can be used between "screw" and "up." I have to concentrate while I do this, so please don't talk and screw me up!

5. noun A huge mistake, blunder, or mishandling. In this usage, the phrase is usually hyphenated or spelled as one word. Another screwup like that and you're fired! I don't care whose screw-up it was—just fix it!

6. noun A person who is prone to making big mistakes or blunders; someone who can't get anything right. In this usage, the phrase is usually hyphenated or spelled as one word. The way I see it, if you treat someone like a screwup their entire life, they're going to eventually become one. I can't believe he married such a screw-up like that.