IPA: /əˌræk.nəˈlɒdʒ.ɪ.kəl/
KK: /əˌræk.nəˈlɒdʒ.ɪ.kəl/
Relating to the study of spiders and other arachnids.
The arachnological research revealed new species of spiders in the rainforest.
Arachnological → It is formed from "arachno-" (from Greek "arachne", meaning spider) and "-logical" (from Greek "logia", meaning study or science). The word refers to the scientific study of spiders and related animals.
Think of 'arachno-' meaning spider and '-logical' meaning study — this helps you remember that 'arachnological' is the study of spiders.