Arabic letter ṣād, initial form

It is the initial form of Arabic letter ص, called ṣād.

Arabic letters can change shape as they join. “Initial” means this form appears at the start of a joining sequence, attached toward the next letter; it is not a separate letter or message. The letter records a consonant, while short vowels are generally left to context or marked separately.

The letter belongs to a historical Semitic family that includes Phoenician ṣade and Hebrew tsadi. Arabic writing developed through Nabataean Aramaic; the earliest dated inscriptions with a full Arabic letter repertoire are placed in the late fifth century CE. The dedicated presentation form ﺻ has a later technical role: compatibility with older character sets.

Why does ص differ across languages?

The spelling can stay while the sound changes.

Arabic distinguishes ṣād from sīn. Persian retains ص mainly in Arabic-derived spellings and pronounces it /s/; Urdu also pronounces ص as /s/ and uses it in words borrowed directly or indirectly from Arabic. So Persian and Urdu readers may hear an ordinary s where Arabic distinguishes a different consonant.

How do I type this exact Arabic form?

Use ص for ordinary Arabic text.

In an Arabic-capable editor, type ص and let contextual shaping give it the right joining form. The dedicated character ﺻ is for cases where that exact compatibility code point matters. Compatibility normalization can map it back to ص, after which the text is shaped according to context.