As per Industrial Dispute Act

Retrenchment means the termination by the employer of the service of a workman for any reason whatsoever, otherwise than as a punishment inflicted by way of disciplinary action, but does not include -

(a) voluntary retirement of the workman; or

(b) retirement of the workman on reaching the age of superannuating if the contract of employment between the employer and the workman concerned contains a stipulation in that behalf; or

(c) termination of the service of the workman as a result of the non-removal of the contract of employment between the employer and the workman concerned on its expiry or of such contract being terminated under a stipulation in that behalf contained therein; or

(d) termination of the service of a workman on the ground of continued ill-health.