Translation guide
In Japanese, 'old rice' typically refers to rice from a previous harvest, not spoiled rice. The most common term is 古米 (こまい), used in contrast to 新米 (しんまい, new rice).
The speaker wants to refer to rice that is not from the current year's harvest, often with a slightly different texture or cooking requirement.
Standard term for rice harvested in a previous year. It is commonly used in grocery stores and cooking contexts.
この古米は炊くときに水を多めにしてください。
When cooking this old rice, please use a bit more water.
Rice harvested two or more years ago. It is even older than 古米 and may have a more noticeable change in quality.
古々米は古米よりもさらに水分を吸収しにくい。
Rice that is two years old absorbs water even less readily than one-year-old rice.
Literally 'last year's rice'. A more casual, descriptive way to refer to old rice.
去年の米がまだ残っている。
We still have some rice from last year left.
The speaker wants to refer to rice that was cooked earlier and has become dry, hard, or stale.
Cold, leftover cooked rice. Often used for fried rice or other dishes.
冷やご飯でチャーハンを作るとパラパラになる。
Using cold leftover rice makes fried rice turn out fluffy and separate.
Leftover rice. A general term for rice that remains after a meal.
残りご飯は冷凍しておくと便利だ。
It's convenient to freeze leftover rice.
The speaker wants to refer to rice that is no longer safe to eat due to age or improper storage.
Spoiled rice (uncooked). Used when rice has gone bad due to moisture, pests, or age.
傷んだ米は臭いがきつい。
Spoiled rice has a strong smell.
Rotten cooked rice. Used when cooked rice has spoiled and is inedible.
夏場は腐ったご飯に注意が必要だ。
In summer, you need to be careful about rice going bad.
新米 (しんまい) is newly harvested rice, prized for its moisture and flavor. 古米 (こまい) is rice from the previous year, which is drier and often requires more water when cooking. In stores, 古米 is cheaper and clearly labeled.
If you mean rice that has been intentionally aged for better flavor (like aged sake rice), that is 熟成米 (じゅくせいまい) or 古酒米 (こしゅまい), not 古米. 古米 simply means non-new-crop rice.