IPA: //mæˈstɔɪdɪtɪs//
KK: /mæˈstɔɪdɪtɪs/
A medical condition characterized by the inflammation of the mastoid bone, which is located behind the ear.
The doctor diagnosed her with mastoiditis after she complained of ear pain and swelling behind her ear.
Mastoiditis → It is formed from "mastoid" (from Greek "mastoeidēs", meaning breast-shaped) and "-itis" (from Greek "itis", meaning inflammation). The word refers to the inflammation of the mastoid process, which is a bony prominence behind the ear that resembles a breast in shape.
Think of the 'breast-shaped' ('mastoid') area behind the ear becoming 'inflamed' ('-itis') — that's what mastoiditis means.