Part of speech: Adjective
relating to or resembling a member of the class Arachnida
The word "arachnoid" comes from Ancient Greek ᾰ̓ρᾰχνοειδής, which was borrowed from New Latin arachnoīdēs.
Arachnida – A related word in the same word family.
-oid – A related word in the same word family.
The Greek language preserved ancient Indo-European roots better than most other languages.