adequation

As a noun adequation

is appropriateness, conformity, adequacy.

As an adjective undefined is

lacking a definition or value.

As nouns the difference between adequacy and adequation

is that adequacy is the quality of being sufficient, adequate or able to meet the needs while adequation is equivalence.

In obsolete terms the difference between adequate and adequation

is that adequate is to equal while adequation is the act of equalizing; act or result of making adequate; an equivalent.

As an adjective adequate

is equal to some requirement; proportionate, or correspondent; fully sufficient; as, powers adequate to a great work; an adequate definition lawfully and physically sufficient.

As a verb adequate

is to equalize; to make adequate.

As a noun adequation is

equivalence.