Sidi or Sayidi, also Sayyidi and Sayeedi, (Arabic: سيدي|Sayyīdī, Sīdī (dialectal) "milord") is an Arabic masculine title of respect. Sidi is used often to mean "saint" or "my master" in Maghrebi Arabic and Egyptian Arabic. Without the first person possessive object pronoun -ī (ي-), the word is used similarly in other dialects, in which case it would be the equivalent to modern popular usage of the English Mr. It is also used in dialects such as Eastern Arabic, as well as by Muslims of the Indian subcontinent in the Urdu language where, however, it does not have as much currency as Sayyid (same spelling: سيد), Janab or Sahib.
Occasionally a respected member of Muslim society will be given the title Sidi by default in recognition of upright standing and wisdom. This especially applies to marabouts, hence the term appears in places and mosques named after one.
In the Hijaz region of Saudi Arabia, the word is used as an honorific when addressing an older brother by many of the more traditional families.
Separate variants and a shift of meaning appeared:
Lalla (of Amazigh origin) when used in a social context, and Sayyeda when speaking about female saints, for example "(Es-)Sayyeda El-Manoubiyya" are female equivalents.
The term was also used by Arabic Spanish, Portuguese, and Berbers in Mozarabic-speaking Moorish Spain (cf. El Cid).