How many letters does the top answer for “the use of the microscope; investigation with the microscope.” have?

The most common answer is microscopy (10 letters).

Crossword clue: the use of the microscope; investigation with the microscope.

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

microscopy 10 letters web-def

research with the use of microscopes

research with the use of microscopes 50% similar → microscopy