Character 亟

It means urgent or repeatedly, depending on the reading.

Read it jí in 亟待, 亟需 and 亟须: something urgently needs doing or solving. Read it qì in classical phrases such as 亟请: someone asked again and again. The word around it picks the reading, so never guess from 亟 alone.

In Shang- and Zhou-period forms, early examples appear on oracle bone, bronze and bamboo-slip writing. The old analysis describes a person between upper and lower limits, with 口 and later 攴 added in bronze forms.

What does 亟 mean when someone sends it?

Treat it as a word, not an emoji-style reaction.

If 亟 arrives alone, ask for the sentence. In a Chinese message the nearby words decide: formal 亟待 and 亟需 point to jí and urgency, while a classical-style 亟请 points to qì and repetition.

Fonts and regional standards can draw the upper part of 亟 differently. That changes the look, not the meaning, so copy it from the palette when a font makes it hard to recognize.

Is 亟 formal?

Yes. Save 亟 for formal writing.

Guidance published in 2021 describes 亟须 as markedly written, while 急需 is normal in both speech and writing. 亟须 usually leads into an action, as in 亟须处理 or 亟须解决. For a casual message, 急需 is safer.