1rare Expensive; sumptuous.
Apparently not attested in the 17th, 18th, or 19th centuries.
2Involving or characterized by expenditure or loss (of time, effort, etc.); costly. Now somewhat archaic.
Apparently not attested in the 16th, 17th, or 18th centuries.
Middle English; earliest use found in Ayenbite of Inwyt. From cost + -ful.