Mouth the words to a recorded song: Hyph

• Fake it, in a way
• "Sing" without singing
• Sing along silently
• Pretend, in a way
• Mouth the lyrics
• Align mouth move­ments with recorded speech
• Go through the motions in a music video?
• Move mouth to fit a soundtrack

Wiktionary Word definitions in Wiktionary
n. (alternative spelling of lip sync English) vb. (alternative spelling of lip-sync English)