How to say "downgrade" in Japanese

• ランクダウン
  nounCovers the sense of moving down a rank, grade, or category, as when something is placed in a lower class than before. A katakana loan-style expression, it is less common than one might expect.
• ダウングレード
  noun, suru verb, transitive verbThe direct katakana borrowing of 'downgrade', used for lowering the level, quality, or rating of something. Less common in Japanese than the English word is, but it is the closest one-to-one match for most senses.
• 下り勾配くだりこうばい
  nounDespite being glossed 'downgrade', this is really the physical sense: a downhill grade or slope on a road or railway track. It is seldom the word you want for lowering status or quality.

For lowering status, quality, or a rating use 「ダウングレード」 (or 「ランクダウン」); 「下り勾配」 is not this sense at all — it means a downhill slope on a road or railway.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• ランクダウンdowngrade
• ダウングレードdowngrade
• 下り勾配くだりこうばいdownhill grade