Tongue-tied

Tongue′-tiedˊ

,

Adj.

1.

Destitute of the power of distinct articulation; having an impediment in the speech, esp. when caused by a short fraenum.

2.

Unable to speak freely, from whatever cause.

Love, therefore, and

tongue-tied

simplicity.

Shakespeare

See also: tonguetied

tongue -tied ‎(comparative more tongue-tied, superlative most tongue-tied)

(idiomatic) Unable to express oneself clearly or fluently; at a loss for words.
If you have never practiced at interviewing for a job, you are likely to have a few tongue-tied moments during your first interview.
Suffering from tongue-tie or ankyloglossia.

unable to express oneself clearly or fluently