costly

As an adjective costly

is of high cost; expensive.

As a preposition worth is

having a value of; proper to be exchanged for.

As a noun worth is

(countable) value.

As a verb worth is

(obsolete|except in set phrases) to be, become, betide.

As adjectives the difference between costly and gratis

is that costly is of high cost; expensive while gratis is (l), without (l).

As an adjective costly

is of high cost; expensive.

As an adverb mostly is

mainly or chiefly; for the most part; usually, generally, on the whole.

As an adverb cosily

is in a cosy manner.

As an adjective costly is

of high cost; expensive.

As a noun taxonomy

is the science or the technique used to make a classification.

As an adjective costly is

of high cost; expensive.

As an adjective costly

is of high cost; expensive.

As a proper noun precious is

.

As adjectives the difference between valuable and costly

is that valuable is having a great value while costly is of high cost; expensive.

As a noun valuable

is a personal possession such as jewellery, of relatively great monetary value; — usually used in plural form.

As adjectives the difference between costly and overcostly

is that costly is of high cost; expensive while overcostly is too costly.

Costly is an antonym of costless.

As adjectives the difference between costly and costless

is that costly is of high cost; expensive while costless is having no cost.