How many letters does the top answer for “several things grouped together or considered as a whole” have?

The most common answer is aggregation (11 letters).

Crossword clue: several things grouped together or considered as a whole

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

aggregation 11 letters wn-def

several things grouped together or considered as a whole

collection 10 letters wn-def

several things grouped together or considered as a whole