invariable

Everyday

1. Invariable means never changing; always the same. tree →
2. (grammar) An invariable word does not change its form, for example «sheep» has the same singular and plural. tree →
3. (maths, rare) An invariable or invariant is a value that stays the same when other things change. tree →

In the lessons

In formal writing and stories it means «always the same»: «his invariable breakfast of toast». In grammar lessons, invariable nouns like «sheep», «deer» and «fish» have the same plural. Related adverb: invariably (always). Phrases: «an invariable rule», «invariable habit».

Examples

• Her invariable answer was «Maybe later». tree →
• Grandpa had an invariable habit of reading the paper after lunch. tree →
• The rule is invariable: no phones in class. tree →
• «Sheep» is an invariable noun: one sheep, two sheep. tree →
• His invariable smile cheered everyone up. tree →
• Nothing in nature is truly invariable. tree →
• The same devices are in almost all cases resorted to, and their effect is invariable. tree →

Note

Adjective, formal. Adverb: invariably (more common: «It invariably rains on sports day»). In- (not) + variable (able to change). Opposite: variable. In maths, «variable» is also a letter that stands for a number, and «constant» is the usual word for a value that does not change.