How many letters does the top answer for “effort expended in moving one object over another with pressure” have?

The most common answer is detrition (9 letters).

Crossword clue: effort expended in moving one object over another with pressure

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

detrition 9 letters wn-def

effort expended in moving one object over another with pressure

rubbing 7 letters wn-def

effort expended in moving one object over another with pressure