The small piece of pink skin that attaches the tongue to the bottom of the mouth is an example of a frenum.
Origin of frenumL, literally , a bridle ; from Indo-European base an unverified form dher-, to hold from source firm
nounpl. fre·nums or fre·na
Origin of frenumLatin fr&emacron;num, bridle, from frendere, to grind; see ghrendh- in Indo-European roots.