The Dragonfly documentation says Dragon Professional Individual version 15 supports English in several variants, plus Dutch, French, German, Italian and Spanish, and it cites Nuance's knowledgebase for other editions.

Checked against its source on October 17, 2026

In the source's own words

“The following languages are supported by Dragon Professional Individual version 15”

Spoken Language Support (Dragonfly documentation), Dragonfly project, Dragonfly documentation (Read the Docs), n.d., Languages supported by Dragon.

What it measures: The page lists languages for each speech engine that Dragonfly can drive. Its Dragon list was taken from Nuance's knowledgebase for the 15 edition. English is counted once here, because the page lists several English variants under one entry.
What it does not show: This is version 15 only, from a third-party page. It does not list Dragon Professional 16 or Dragon Home, and it does not list Japanese. Confirm the current list with Nuance before you buy.