monastic vs monastical

monastic is a noun but monastical is not a noun.

Word	Noun	Adjective	Verb	Adverb
monastic	Yes	Yes	No	No
monastical	No	Yes	No	No

As adjectives, monastic and monastical are synonyms defined as:

monastic and monastical: of communal life sequestered from the world under religious vows

Other synonyms of monastic include cloistered, cloistral, conventual.

monastic (noun)	monastical (noun)
a male religious living in a cloister and devoting himself to contemplation and prayer and work

monastic (adjective)	monastical (adjective)
of communal life sequestered from the world under religious vows	of communal life sequestered from the world under religious vows