一般的定义：

「On-sight」：事前不知道该路线的攀爬信息，第一次爬该路线就无坠落成功地完攀。
Climbing a route for the first time and not falling, without having been given any previous information concerning the route.

「Redpoint」：事前曾练习爬过该路线，以先锋攀登的方式、无坠落地完攀该路线。
To successfully climb a route on lead, without falling, after practice or rehearsal of required sequence.

较严谨的定义：

「On-sight」：定义同上，要自己挂快扣。

「Redpoint」：定义同上，要自己挂快扣。
To lead a route, clipping protection as you go, without falling or resting on pro.

「Flash」：定义同on-sight，要自己挂快扣，事前可以知道攀爬信息（例如看别人爬、问别人怎爬）
to climb a route first try without ever having touched the route, but with the aid of beta.

「Pinkpoint」：定义同on-sight，快扣已挂在上面，只须把绳子挂进快扣中即可。
To lead (without falling) a climb that has been pre-protected with anchors rigged with carabiners.

其它：

「Hangdogging」：爬路线中途，会利用绳子受力休息。
”Climbing” a route, usuallying bolt to bolt, with the aid of the rope to hang and rest.
When a leader hangs from a piece of protection to rest, then continues on without lowering back to the ground; not a free ascent.

参考资料：
Eric J. Horst, 「How to climb 5.12」, 1997
Heather Reynolds Sagar, 「Climbing your Best」,2001
John Long, 「How to Rock Climb!」, 1998

如有错误或误解意义的地方,请不吝指教~