English Reference
Noun

caustic

n.
C1 Advanced US /ˈkɑstɪk/ UK /kˈɔːstɪk/ caus·tic UK spelling caustics Chemistry Mathematics

n.a substance that can burn or damage things it touches. It is often used to describe strong chemicals like bleach or acid.

n.a substance that is capable of burning or corroding living tissue or other organic matter. Often used to describe strong alkalis or acids that cause chemical burns upon contact.


SIMPLE

The worker wore thick gloves to handle the caustic cleaner.

CONTEXTUAL

The lab safety manual warns that the caustic solution must be diluted before it is poured down the drain.

COMPLEX

While the chemical is essential for industrial cleaning, its caustic nature requires strict safety protocols to prevent accidental exposure to the skin or eyes.

For me, its winning blend of caustic discomfort and a big heart also evokes that other great TV love story: Tim and Dawn in the original UK run of The Office.

The Guardian· 8 Sept 2026

Vulture is a caustic study of what it means to report from a conflict, and particularly relevant to the current moment.

The Guardian· 20 Aug 2026

From the Latin causticus (“burning”), from Ancient Greek καυστικός (kaustikós, “burning”), from καυστός (kaustós, “burnt”) + -ικός (-ikós).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Ancient Greek καυστικός
Level C1 · Advanced
Frequency Occasional
Updated