frenulumyoudaoicibaDictYouDict[frenulum 词源字典]
"A small fold or ridge of tissue which supports or checks the motion of the part to which it is attached, in particular a fold of skin beneath the tongue, or between the lip and the gum", Early 18th century: modern Latin, diminutive of Latin frenum 'bridle'.[frenulum etymology, frenulum origin, 英语词源]