rain check

WordReference Random House Learner's Dictionary of American English © 2025

ˈrain ˌcheck or ˈrainˌcheck, n. [countable]

1. an offered or requested postponement of an invitation until a more convenient time.
2. a ticket or piece of paper allowing a customer to buy an out-of-stock sale item at a later date for the sale price.
3. a ticket for future use given to customers at an outdoor event that has been postponed or interrupted by rain.

WordReference Random House Unabridged Dictionary of American English © 2025

rain′ check′, 

1. a ticket for future use given to spectators at an outdoor event, as a baseball game or concert, that has been postponed or interrupted by rain.
2. an offered or requested postponement of an invitation until a more convenient, usually unspecified time:
   Since you can't join us for dinner, we'll give you a rain check.
3. a ticket, coupon, or the like, entitling a customer to purchase at a later date and for the same amount a sale item that is temporarily out of stock. Also, rain′check′. 
• 1880–85