アディショナルMeanings1noun-modifying (irregular)additionalLoanword from English 'additional', used prenominally to modify nouns. Common in business, IT, and formal contexts.アディショナルな情じょう報ほうが必ひつ要ようです。Additional information is needed.アディショナルタイムにゴールが決きまった。A goal was scored in additional time.