'hygienic' originates from Greek via French, specifically from French 'hygiénique' and ultimately from Greek 'hygieinós' (related to 'Hygieia'), where the root 'hygie-' meant 'healthy'.

'hygienic' changed from Greek 'hygieinós' into French 'hygiénique' and later entered English in the 19th century as the modern adjective 'hygienic'; 'hygienically' is the adverbial form formed in English.

Initially it meant 'pertaining to health' (in the sense of 'healthy'); over time it evolved to its modern sense emphasizing cleanliness and measures that prevent disease ('promoting or ensuring cleanliness and public health').