n.
原子笔

[ noun ]
a pen that has a small metal ball as the point of transfer of ink to paper
<noun.artifact>

ballpoint \ballpoint\ n.
a pen which has a small metal ball as point of transfer of
ink to paper, at the tip of a cylandrical and non-refillable
reservoir of ink; -- short for {ballpoint pen}.

Syn: ballpoint pen, ballpen, Biro.
[WordNet 1.5]