Verb:CURSE

The curse verb can be used by itself, which would look something like:

>curse
You curse the day you were born.

>curse {target}
You let loose with an involved curse detailing the improbable ancestry of {target}.

Additionally the curse command ties in with the Curse (715) spell.
CURSE HELP shows how this aspect of the verb works:

>curse help

Usage:
    CURSE [target] [cursename]

For further information:
    CURSE LIST
    CURSE HELP {cursename}
    CURSE HELP POWER

Your cursing power is 209.

CURSE LIST shows what curse options are available to a caster. Information on each curse can be found with CURSE HELP {cursename}. The asterisk-marked curses are those that the caster can utilize. As the spell-user grows in power, so do the curse-choices.

>curse list
The following is a list of all known curses.  For information on each one, type CURSE HELP {cursename}.  Those marked with an asterisk are within your power to cast.

(*) Clumsy
(*) Weakness
(*) Darkness
(*) Itch
(*) Hex
(*) Pox
(*) Nightmare
(*) Star

CURSE HELP POWER refers to the caster's ability as it pertains to the Curse (715) spell and to what curse-choices are available, thus it can largely be ignored when it comes to the casting process itself. Type CURSE HELP to find your current power.