How many letters does the top answer for “lack of courage; cowardliness.” have?

The most common answer is discourage (10 letters).

Crossword clue: lack of courage; cowardliness.

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

discourage 10 letters web-def

try to prevent; show opposition to

with a lack of courage and determination 50% similar → pusillanimously, simperingly