vary

Vary is a verb with senses centered on difference and change. In its intransitive use, it describes something that is not constant: prices vary by region; opinions vary from person to person. In its transitive use, it means to change something: researchers varied the conditions of the experiment. It is commonly followed by by, from, to, or with: vary by region, vary from 5 to 20 dollars, vary the dosage.

The noun form is variation, and the adjective forms are variable and varying. Phrases such as vary greatly, vary widely, vary depending on, and vary between are frequently used to express extent or dependence on context.

Etymology traces vary to Latin varius, meaning "different, changing," and it passed into English via Old French. Related words include variety, variety, variable, and variation, which share the core idea of difference or change.

In science and mathematics, vary is used to describe change in parameters or conditions. To vary a parameter means to alter its value in order to observe effects. Variation is the resulting degree of difference across values, samples, or time. In statistics and experimental design, outcomes may vary across groups or treatments, reflecting natural or systematic differences.

Usage notes: avoid confusing senses by ensuring a direct object is present when meaning “to change something” and none is needed when indicating a difference. Common collocations emphasize scale and dependence, such as vary greatly, vary by region, or vary over time.