impervious

Merriam-Webster's Word of the Day for May 15, 2025 is:

impervious • \im-PER-vee-us\  • adjective

Impervious describes that which does not allow something (such as water or light) to enter or pass through. It is also used formally to mean “not bothered or affected by something.” Both senses of impervious are usually used with to.

// The material is impervious to water.

// The mayor seems impervious to criticism.

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Examples:

“All of this ups the already sky-high stakes for ‘Superman,’ which relaunches the DC Universe under the direction of Gunn and Peter Safran. The film is the studio’s best hope at fielding a billion-dollar blockbuster in 2025, but even the Man of Steel isn’t impervious to box office Kryptonite.” — Rebecca Rubin, Variety, 17 Jan. 2025

Did you know?

Finding your way through some words’ etymologies can lead to surprising discoveries of origins that seemingly have little to do with their modern-day meanings. Impervious, which entered English in the early 1600s, is not one of those words—its history is entirely straightforward. The Latin ancestor of impervious is impervius, which adds the prefix im-, meaning “not,” to pervius, meaning “passable or penetrable.” Pervius in turn comes from per, meaning “through,” and via, meaning “way.” Impervious, it follows, describes things that don’t allow a way through something, whether literally (as in “asphalt, concrete, and other surfaces that are impervious to rain”) or figuratively (as in “impervious to criticism/pressure”). The opposite of impervious, pervious, entered English at around the same time, but it is much less common.