adverb
suddenly; all at once; rapidly
Describes a sudden, often noticeable change or occurrence. Somewhat literary or formal in tone.
秋になると、とみに涼しくなる。
When autumn comes, it suddenly becomes cool.
彼の病状はとみに悪化した。
His condition rapidly worsened.
急に is the common, everyday word for 'suddenly'. とみに is more literary and often implies a noticeable change over a short period.
突然 is a neutral, widely used adverb for unexpected events. とみに carries a slightly more formal or written nuance.
Derived from the classical Japanese adjective 頓し (とみし), meaning 'sudden' or 'abrupt'. The adverbial form とみに has survived into modern Japanese as a somewhat literary expression.