[Rutherford]

Why is adamantane (http://www.drugbank.ca/drugs/DB03627/structure?dim=3d) called Tricyclo[3.3.1.1]decane?
Trycyclo- is because three cycles form adamantane (the "4^th" is produced from the three).
Why is [3.3.1.1] in the brackets? Could someone mark the bridges in adamantane to which these numbers belong?

[sjb]

See e.g. http://dx.doi.org/10.1351/pac199971030531

[kriggy]

Its tricyklo[3.3.1.1^3.7]decane
3.3.1.1 means number of carbons in that cycle 3 means 3 carbons in that cycle and 1 means amount of carbons in bridge. The carbons where the 1st bridge connects doesnt count.
hope this image helps

and btw there is no 4th cycle.

[Rutherford]

Okay, thanks.