'flock' originates from Old English, specifically the word 'flocc', where the root meant 'a tuft or group (of people or animals)'.

'flocc' in Old English continued into Middle English as 'flokk/flok' and eventually became the modern English word 'flock'.

Initially it often referred to a 'tuft' or 'lock' (of hair) and to a 'group', but over time the predominant meaning focused on a 'group of animals or people' (which remains the main meaning today).