1. To swear on your life. Similar to "swear to God" or "swova," swife denotes that the speaker is placing a huge amount of credibility on his statement, due to the fact that he has laid his life down as collateral in order to provide credibility.
Used to filter comments in serious situations, where it is imperative that one know whether or not someone is being serious, or just kidding.
Guy #2: Swife? (ie. Do you swear on your life?)
Guy #1: Yes!
Guy #2: !*#@!
"Hello George! Hello El... Whose this? Where's Eleanor?"
"Eleanor is with a buddy of mine. This is my SWIFE for the week, her name is Sharon."
"Oh. Gee, maybe you could be MY swife sometime?"
"Sure, that is if you got a tasty fox for my husband. Let me get my planner."