PREPAID

postpaid, prepaid

(adjective) used especially of mail; paid in advance

PREPAY

prepay

(verb) pay for something before receiving it

Source: WordNet® 3.1

Verb

prepaid

simple past tense and past participle of prepay

Adjective

prepaid (not comparable)

paid for in advance

Source: Wiktionary

PREPAY

Pre*pay", v. t. [imp. & p. p. Prepaid; p. pr. & vb. n. Prepaying.]

Definition: To pay in advance, or beforehand; as, to prepay postage.

Source: Webster’s Unabridged Dictionary 1913 Edition