noun
user dictionary
A custom dictionary file or list where a user can register words, often used in IMEs, spell checkers, or text input systems.
このIMEでは、ユーザー辞書に単語を追加できます。
In this IME, you can add words to the user dictionary.
辞書 is a general dictionary, while ユーザー辞書 is a user-specific custom dictionary, often for software.
Compound of ユーザー (user) and 辞書 (dictionary), a straightforward modern computing term.