a reply of acknowledgement, a verbalabbreviation of "I got you", which is derived from "I got what you're saying".
me: "I'm staying in tonight."
her: "why? you not feeling well?"
me: "nope. I'm cuffed."
her: "gotcha. oh well don't worry about it. I got cash. I'll be there in 5, see you soon."
me: "sweet."
Explicative shouted after screwing someone over big time, but the fact that you said "gotcha" makes it all OK.
Sue - "They towed my car! Unbelievable! I saw you put the money into the parking meter though"
Jack - "Actually I just pretended to put money in, I pocketed it instead"
Sue - "Jack! Thats a $90 fee! You idiot!"
Jack - "Gotcha!"
Sue - "Haha! Oh Jack..."
The perfect word to kill a conversation you don't feel like having. When texted, it's effects are similar to a singular "haha," "nice," and "cool."
Boy: Hey, Candice, how's it going?
Girl: Good.
Boy: A bunch of us are going to the movieslater if you want to come with.
Girl: I have a lot of stuff to do. I'll let you know tho.
Boy: Ok! We're going to see Star Wars. It's sold out but my friend has tickets.
Girl: Gotcha.