Translation guide
A hard-boiled egg is an egg cooked in its shell in boiling water until both the white and yolk are solid. In Japanese, the most common term is ゆで卵, but there are specific words for different cooking methods and contexts.
To refer to a hard-boiled egg in everyday conversation, such as in cooking, lunch boxes, or as a snack.
The standard, everyday word for a boiled egg. It can refer to both hard-boiled and soft-boiled eggs, but context usually clarifies the doneness. If you need to specify 'hard-boiled', you can say 固ゆで卵.
ゆで卵 is the general term for boiled eggs and can be either hard or soft. 固ゆで卵 explicitly means hard-boiled (solid yolk). 半熟卵 (はんじゅくたまご) means soft-boiled egg with a runny or jammy yolk. In many contexts, ゆで卵 alone is understood as hard-boiled unless specified otherwise.
If you want a hard-boiled egg at a ramen shop, you might ask for 味付け玉子 (あじつけたまご) or 煮卵 (にたまご), which are seasoned boiled eggs, not plain hard-boiled eggs. A plain hard-boiled egg is less common as a topping.
I ate a hard-boiled egg for breakfast.
I put a hard-boiled egg in the lunch box.
Specifically means 'hard-boiled egg', emphasizing that the yolk is fully solid. Use this when you need to distinguish from soft-boiled.
To make hard-boiled eggs, boil them for 12 minutes.
A hard-boiled egg that has been peeled and simmered in a seasoned broth (usually soy sauce, mirin, etc.). Common as a ramen topping. Not a plain hard-boiled egg.
I topped my ramen with a seasoned boiled egg.