tongue-tied

adjective4

1. •
   Having tongue-tie or ankyloglossia (“a congenital oral anomaly in which the lingual frenulum (a membrane connecting the underside of the tongue to the floor of the mouth) is unusually short and thick, decreasing mobility of the tongue and affecting eating, speech, etc.”).
2. •
   (figurative) Prevented from or unable to express oneself clearly or fluently, or freely; at a loss for words, speechless.

   • My toung-tide Muse in manners holds her still, / While comments of your praise richly compil'd, / Reserue their Character with goulden quill, / And precious phrase by all the Muses fil'd. — 1609
3. •
   (figurative) Reluctant to speak up; reserved, reticent.

   • Tongue-tied or short of breath / Don't even try — 1983
4. •
   (literary, figurative) Physically unable to speak; dumb, mute.