In reply to Stevie989:
If you say 'onsight second' everyone knows what you mean. It is obviously not the same as a trad lead onsight, since there is a rope leading the way, but nobody will think it is as long as it is accurately described.
Perhaps the route is winding and you spend most of it unable to watch your leader? Perhaps you don't pay any attention to the moves, so acquire minimal/no beta? Or perhaps your leader points out some critical hold to you, or works a tricky move in front of you, and you get some beta - now it is a flash, not an onsight.
Personally I am quite good at completely failing to pay any attention to what the leader is doing in climbing terms...