Definitions of pat:

• noun:   the sound made by a gentle blow
• noun:   a light touch or stroke
• verb:   hit lightly

  Example: "Pat him on the shoulder"

• verb:   pat or squeeze fondly or playfully, especially under the chin
• adjective:   exactly suited to the occasion

  Example: "A pat reply"

• adjective:   having only superficial plausibility
• adverb:   completely or perfectly

  Example: "He has the lesson pat"

• name:  A female given name (common: 1 in 2500 females; popularity rank in the U.S.: #387)
• name:  A male given name (common: 1 in 4545 males; popularity rank in the U.S.: #457)
• name:  A surname (very rare: popularity rank in the U.S.: #50087)