Opera is actually a plural; the singular is opus, meaning "work." But when we treat opera as an English word meaning a long musical composition of vocal and orchestral p…arts, we pluralize it as operas.(MORE)
It depends on which type of brush you mean. If you men a brush as in a shrubbery, then the word brush is plural and singular. To be lost in the brush implies that you ar…e in an area that is full of bushes or shrubberies. If you mean a brush that you use in your hair, then the plural is brushes. (MORE)
"Instruction" is standard noun derived from French derived from Latin. As with most words like this the plural is formed by adding an 's' on the end. The teacher gave hi…s students the instructions needed to make a paper aeroplane. (MORE)
The word perfume can be a group noun if referring to the industry, or to scented materials as a whole. But having more than one perfume would have the normal form "perfumes", …e.g. She purchased various perfumes.(MORE)
Uncountable nouns are words for things or ideas that can't be divided into separate elements; they can't be counted. Examples of singular, uncountable nouns are: … advice aluminum concrete cooperation education electricity fishing happiness helium hockey homework information knowledge money music news oxygen police shopping weather (MORE)