'anomalistic' originates from Greek, specifically the word 'anomalos', where 'an-' meant 'not' and 'homalos' meant 'even' or 'level'.

'anomalos' passed into Late Latin/Medieval Latin as 'anomalia'/'anomalus', entered English as 'anomaly' and 'anomalous', and the adjective form 'anomalistic' (and its adverb 'anomalistically') was formed in English by adding the suffix '-istic'/'-ically'.

Initially it meant 'uneven' or 'irregular'; over time it has come to mean 'relating to or characterized by anomalies' or more generally 'deviating from the norm'.