Çavuş, also anglicized Chaush and Chiaus (from Turkish: çavuş / چاوش, "messenger"), Arabic 'shawish, شاويش', (from Old Turkic Çabuş or Çawuş, "person who gives order, person who yells") was an Ottoman title used for two separate soldier professions, both acting as messengers although differing in levels. It was a rank below agha and kethüda (from Persian, kad-khuda, "magistrate"), in units such as the Janissaries and Sipahi, and was also a term for members of the specialized unit of çavuşān (چاوشان, also çavuşiyye, çavuş(an)-i divan(i)) consisting of combined cavalry and infantry serving the Imperial Council (as in Ottoman Egypt). The leaders of the council's çavuş were titled çavuşbaşı / چاوش باشی (or başçavuş / باش چاوش). The çavuşbaşı was an assistant (or deputy) to the Grand Vizier, dealing with security matters, accompanying ambassadors visiting the Grand Vizier, and also carried out the first examination of petitions submitted to the Council, and led council meetings when the Grand Vizier was not present. The title has its origin in Uyghur use, where it was the title of ambassadors, and then entered Seljuq use for Byzantine imperial messengers, and Persian and Arabic use for various court attendants.

The word gave rise to surnames, such as Çavuş (Turkish), Çavuşoğlu (Turkish), Čaušević (Serbo-Croatian), Čaušić (Serbo-Croatian), Baščaušević (Serbo-Croatian), Çaushaj (Albanian), Ceaușu (Romanian), Ceaușescu (Romanian), Τσαούσης (Tsaousis in Greek), and others. It is also the stem of place names, such as Çavuş (in Turkey), Çavuşlu (in Turkey), Çavuşlar (in Turkey), Çavuşköy (in Turkey), Çavuşbayırı (in Turkey), Čauševac (in Bosnia), Čauševići (one village in Bosnia and one village in Serbia), Čaušev Do (in Bosnia), Čauševina (in Bosnia), Čaušlije (in Bosnia), Čaušlija (in Macedonia), Chavusy (in Belarus), Çaushi (in Albania), and others. In the past in former Yugoslavia, the word čauš was also sometimes applied to the wedding-planner.