'shirk' (base of 'shirker') originates from Middle English, specifically the word 'shirken' (attested in later Middle English), where the precise root is uncertain but it conveyed the idea of turning away or avoiding.

'shirk' changed from Middle English 'shirken' and later became the modern English verb 'shirk'; the noun 'shirker' developed from the verb to denote a person who shirks.

Initially it carried the sense of 'turning aside, shrinking away,' but over time it evolved into the current core meaning of 'avoiding work, duty, or responsibility.'