How many letters does the top answer for “another word for completing” have?

The most common answer is complemental (12 letters).

Crossword clue: another word for completing

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

complemental 12 letters gen-syn

acting as or providing a complement (something that completes the whole)

complementary 13 letters gen-syn

either one of two chromatic colors that when mixed together give white (in the case of lights) or grey (in the case of p

another word for about 50% similar → approximately, roughly, some

another word for terms 50% similar → footing

another word for under 50% similar → nether

another word for word 50% similar → phrase