A voiced postalveolar or palato-alveolar fricative is a type of consonantal sound used in some spoken languages. The International Phonetic Association uses the term voiced postalveolar fricative only for the sound [ʒ], but it also describes the voiced postalveolar non-sibilant fricative [ɹ̠˔], for which there are significant perceptual differences, as one is a sibilant and one is not.
Ĵ or ĵ (J circumflex) is a letter in Esperanto orthography representing the sound [ʒ].
While Esperanto orthography uses a diacritic for its four postalveolar consonants, as do the Latin-based Slavic alphabets, the base letters are Romano-Germanic. Ĵ is based on the French pronunciation of the letter j to better preserve the shape of borrowings from that language (such as ĵurnalo from journal) than Slavic ž would.