'autocorrelate' is a modern English formation combining the prefix 'auto-' (from Greek 'autos', meaning 'self') and the verb 'correlate' (from Latin-rooted English 'correlate', meaning 'to establish a mutual relationship').

'correlate' developed in English from Late Latin/Neo-Latin formations (related to Latin elements 'com-/cor-' meaning 'together' and 'relatus/relate' meaning 'brought/related'); in the 20th century the technical prefix 'auto-' was attached in statistics and signal processing to form the compound 'autocorrelate'.

Originally 'correlate' meant 'to bring into mutual relation'; when combined as 'autocorrelate' it came to mean specifically 'to relate or compare something with itself' and is now used chiefly for calculating or describing autocorrelation in statistics and signal processing.