Curiosity is a desire to know about something.
e.g. Ryle accepted more out of curiosity than anything else...
e.g. ...an enthusiasm and genuine curiosity about the past...
A curiosity is something that is unusual, interesting, and fairly rare.
e.g. There is much to see in the way of castles, curiosities, and museums...
e.g. Reed International is a curiosity in the international world of publishing.
3. curiosity killed the cat -> see cat