'antimechanistically' originates from Modern English, specifically formed from the Greek prefix 'anti-' (from Ancient Greek 'ἀντί') meaning 'against' plus the adjective 'mechanistic' ultimately derived from Greek 'mēkhanē' (μηχανή) meaning 'device/contrivance' via Latin 'mechanicus', with the adverbial suffix '-ally'.

'antimechanistically' developed as the adverbial form of 'antimechanistic', which itself was created by prefixing 'anti-' to 'mechanistic' (the latter evolving from Greek 'mēkhanē' → Latin 'mechanicus' → Middle/Modern English 'mechanic/mechanistic'), and then adding the adverbial ending to produce 'antimechanistically' in modern usage.

Initially it carried the sense 'in a manner opposed to machine-like or mechanistic explanations'; over time the meaning has remained largely stable as 'in a way opposed to mechanistic or reductionist explanation'.