A simple clipping, usually about 1 cm, done with sterile scissors of the lingual frenulum in cases where it is too short, tight or inserted too close to the tip of the tongue. It is done to "release" the tongue so it can move more freely; for breastfeeding, for speech, for social play (sticking out the tongue, licking ice cream cones, kissing). This is to be contrasted with a frenectomy, a much more invasive surgery, involving removal of vascular and highly innervated tissue, not just clipping of a thin fibrous membrane. Frenotomies done on infants ususally involve no more bleeding than a dime sized stain and the baby can breastfeed immediately afterwards. They are best done only IF needed to allow effective breastfeeding in the first days of life, before abnormal feeding behaviors are learned.


SOURCES
http://www.bartleby.com/61/1/F0320100.html
http://www.anatomy.usyd.edu.au/glossary/glossary
http://www.ucd.ie/~vetanat/ga-subject/pelvis/pl4.html.
http://www.brianpalmerdds.com/frenum_pdf.pdf