Puruṣa: There are several derivations for this word. One derivation means ‘one who resides in the body’, the second one means ‘one who fills (permeates) the body’. Some of the given meanings are – human being, soul, spirit and supreme soul, consciousness (in contrast to prakṛti). The derivation drives home the philosophies of yoga and sāṅkya, that of essential duality of the soul and the body. Yoga philosophy presents God, called Īśvara (etymologically it means The Lord) as a special puruṣa unsullied by the load of kleśa, karma, results of karma (Sūtra 1.24) unlike all other infinite number of puruṣa-s. Sāṅkya system does not mention  Īśvara.
The goal of yoga philosophy and practice (called sādhana / abhyāsa) is  kaivalya (oneness), that is, for the puruṣa to disentangle from the fold of  prakṛti, representing the body, mind and its fluctuations.