Definitions of chap:

• noun:   (usually in the plural) leather leggings without a seat; joined by a belt; often have flared outer flaps; worn over trousers by cowboys to protect their legs
• noun:   a crack in a lip caused usually by cold
• noun:   a boy or man

  Example: "That chap is your host"

• noun:   a long narrow depression in a surface
• verb:   crack due to dehydration

  Example: "My lips chap in this dry weather"