What is the meaning of ʻ?

Spiritus asper used in Wade-Giles romanization of Mandarin Chinese.

aspiration.

(light) aspiration.

transliteration of the Semitic letter ayin.

Transliterates Perso-Arabic letter ع in Indic languages.

The thirteenth letter of the Hawaiian alphabet, called ʻokina and written in the Latin script.

the alveolar clicks, modern ⟨ǃ⟩. (Besides the plain letter ⟨ʻ⟩, this is used for the alveolar click consonants ⟨ʻk ʻg ʻn ʻh ʻkh⟩.)

A letter of the Tahitian alphabet, the ʻeta.

The seventeenth letter of the Tongan alphabet, called fakauʻa and written in the Latin script.

Source: wiktionary.org