scales
n. C / Un. a tool used for measuring how heavy something is. You can also use this word for the small, hard plates that cover the skin of a fish or snake.
n. an instrument or machine used for weighing; also refers to the small, overlapping plates forming the protective outer covering of fish and reptiles. Often used in the plural when referring to the weighing apparatus.
I stepped on the scales to check my weight.
The chef carefully placed the ingredients on the kitchen scales to ensure the recipe was perfectly balanced.
While the biologist examined the iridescent scales of the specimen under a microscope, the lab assistant recorded the creature's total mass using a set of precision digital scales.
When referring to a weighing device, the word is frequently used in the plural ('scales') even for a single machine.
The fish has many scaleThe fish has many scalesWhen referring to the skin of an animal, the noun is countable and requires the plural form to describe the whole covering.