How many letters does the top answer for “on, or toward, the dorsum, or back; on the dorsal side of; dorsad.” have?

The most common answer is dorsally (8 letters).

Crossword clue: on, or toward, the dorsum, or back; on the dorsal side of; dorsad.

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

dorsally 8 letters web-def

in a dorsal location or direction