'nematode' originates from New Latin, specifically the Neo-Latin 'Nematoda', from Greek 'nēmatōdēs' where 'nēma' meant 'thread' and '-ōdēs' meant 'like' or 'having the form of'.

'nematode' was formed from the Greek adjective 'nēmatōdēs' → New Latin 'Nematoda' (used in scientific classification) → adopted into English in the 19th century as 'nematode' to name members of the phylum Nematoda.

Initially it described 'thread-like' form; over time it became the standard term for the group of roundworms (phylum Nematoda) and for specific parasitic species within that group.