Such are many names of qualities (as cheerfulness, mirth), of sciences (as chemistry[15]), of forces (as gravitation).

Many nouns, commonly used in the singular only, may take a plural in some special sense. Thus,—

earth (the globe)earths (kinds of soil)
ice (frozen water) ices (food)
tin (a metal) tins (tin dishes or cans)
nickel (a metal) nickels (coins)

83. Some nouns are used in the plural only.

Such are:

84. A few nouns are plural in form, but singular in meaning.

Such are: