na-adjective
A straightforward loanword from English 'impressive', used as a な-adjective. Common in casual and semi-formal contexts, often in speech or informal writing.
彼のプレゼンは本当にインプレッシブだった。
His presentation was really impressive.
あの映画の特殊効果はインプレッシブだね。
The special effects in that movie are impressive, aren't they?