Peyer's patch
noun
Pey·er's patch
| \ ˈpī-ərz-
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Medical Definition of Peyer's patch
: any of numerous large oval patches of closely aggregated nodules of lymphoid tissue in the walls of the small intestine especially in the ileum that partially or entirely disappear in advanced life and in typhoid fever become the seat of ulcers which may perforate the intestines
— called also Peyer's gland