Many Christians attempt to define the word to mean an 180 degree turn from your sins...under the context of the believer, I might somewhat agree, but not for the unbeliever. The unbeliever does not turn from their sins to get saved, they simply reconsider the truth of the gospel and believe ((Mark 1:15 NASB) and saying, "The time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel."
Salvation is a free gift of God, anything we do (including "turning from our sins") outside of receiving His gift of grace is attempting to merit His favor...that's not salvation. The bottom line: are you trusting in the finished work of Christ on the cross or something else for your salvation. Consider again or rethink what/who you're trusting in and trust Christ alone...that's repentance unto life eternal.
Check out an excellent theological article on the subject at: