title lettering; title calligraphy
Refers to the characters written on the cover or title page of a book, magazine, or other publication, often done in calligraphy.
The title lettering of this book was written by a famous calligrapher.
A famous calligrapher wrote the title lettering for this book.
They put gold title lettering on the cover.
The editor-in-chief asked a famous writer to do the title calligraphy.
タイトル is a general, casual loanword for a title, while 題字 specifically denotes the calligraphic lettering of a title on a publication.
題目 means the topic or theme of a work (e.g. a speech or essay), not the written lettering of a title, despite sharing the kanji 題 with 題字.
Compound of 題 (title, topic) and 字 (character, letter).