To entangle is to snarl, intertwine with, or get caught in. Too often, dolphins entangle themselves in large fishing nets meant to catch tuna or swordfish.
If you mean to trip your brother, you can entangle your leg around his, and when long-haired people don't brush it for days, it will snarl and entangle itself. A figurative way to entangle is to get caught up in a complicated situation: "I didn't mean to entangle you in this mess with my roommates!" Entangle's roots are en-, "put in" or "cause to be" and tangle, or "snarl."