How many letters does the top answer for “lack of movement or room for movement” have?

The most common answer is tautness (8 letters).

Crossword clue: lack of movement or room for movement

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

tautness 8 letters wn-def

lack of movement or room for movement

tightness 9 letters wn-def

lack of movement or room for movement

a lack of coordination of movements 50% similar → incoordination