Supernumerary
Beyond the normal number. Anything supernumerary is extra. A supernumerary chromosome is an extra one beyond the usual number of 46. A supernumerary digit is an extra finger or toe. A supernumerary nipple is an extra nipple beyond the usual one on either side. A supernumerary placenta is an extra placenta (afterbirth) and is called an accessory or succenturiate placenta.
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su·per·nu·mer·ary .sü-pər-'n(y)ü-mə-.rer-ē, -'n(y)üm-(ə-)rē adj exceeding the usual or normal number
<\supernumerary teeth> <a \supernumerary rib>
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n.
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su·per·nu·mer·ary (soo″pər-nooґmər-ar″e) [L. supernumerarius] in excess of the regular or normal number.
Medical dictionary.
2011.