Sinha is a Sanskrit term originates from South Asia, used as a common term mainly in India and Sri Lanka. It comes from the Sanskrit word "Siṃha" ('ng' sound), which means lion.
In Sri Lanka, the term 'Sinha' (or Siha / Sinhe / Singhe / Singha) have commonly been used by the Sinhalese (or Sinhala). When it comes to the term 'Sinhala' it self, the first part of the word, 'Sinha' stands for 'lion' while 'la' or 'le' stands for 'Blood', giving the meaning 'Lions blood'. The word Simhmam (or Singam / Singham / Singhai / Singai) is the Sri Lankan Tamil derivative.
The more common surnames, "Singh" in India and "Weerasingha", "Jayasinghe ", "Wijesinghe", "Edirisinghe", "Singaiariyan" etc. in Sri Lanka share this same root. As a surname, Sinha is mainly used by Kandyan, Kshatriy (Kurmi), Kayasthas and Rajputs as well as some Brahmins (Bhumihar) . In Orissa and South West Bengal (Northern Rurh region-Burdwan belt), Sinha is also a shortened version of the surname Singha-Maha-Patra, a Utkal Brahmin surname. In Gujarat, the Sinha surname is mostly used by Vaishnav Vaniyas, a trader class.
Sinha is also an unrelated name found in Brazil.