Cast

If your character has the ability, there are two ways to use a spell: casting and invoking.

From "help cast:"

Cast:

Usage: cast '<spell name>'
Usage: cast '<spell name>' <target>

Casting is the ancient art of gathering one's magical energies into
powerful offensive and defensive spells, often aided by the recitation of
certain scrolls, or drinking of certain fluids and mixtures. To cast a
spell, simply type " cast '<spellname>' " It is very important you include
the single quotation marks, or else your spell will not be properly cast.
Your magical energies are proportional to your attributes of wisdom and
intellect; naturally, having higher statistics in these fields will greatly 
enhance your spell-casting ability. As magical energies are the basis for 
nearly all spells, it requires less magical energy to cast a spell than it 
does to invoke one. Note that many spells are both castable and invokable.

The art of casting, although requiring patience and concentration, can be 
made simpler by Nodeka's automatic word-finishing system. This means you 
need not chant ALL the words in a spell to cast it. For example, extrinsic 
elucidation need not be cast by typing, in full, cast 'extrinsic 
elucidation'. c 'ex el' will work just as well, as will other variations 
allowing Nodeka to finish single/multiple word combinations in spells.