CJK Compatibility Ideograph FA55

It means 突: thrusting, protrusion, or suddenness. Japanese references list 突 as the old form of 突, not a separate word. In compounds, 突然 means “suddenly” and 突起 means “projection.”

The history of 突 predates the compatibility code point. The Shuowen Jiezi, a dictionary compiled during the Han dynasty, glosses 突 as a dog briefly emerging from a cave; Chinese and Japanese dictionaries trace related senses of thrusting, protruding, and suddenness to that movement. The separate U+FA55 entry came later: JIS X 0213:2000 assigned it a source mapping so Japanese text could travel into Unicode and back without losing the distinction.

Why does 突 become 突?

Normalization can turn 突 into 突 and erase its source distinction. Unicode maps this character to 突; normalization can apply that mapping even if the displayed outline does not visibly change.

Use 突 only when preserving a legacy Japanese source or testing a conversion path; ordinary Chinese and Japanese writing uses 突. To keep the distinction, avoid normalization and verify the code point after conversion. If your font draws the two alike, their appearance cannot tell you which character survived.