'uncensorious' originates from English, specifically formed from the prefix 'un-' and the adjective 'censorious', where 'un-' meant 'not' and 'censorious' ultimately derives from Latin 'cēnsor' / 'censēre' meaning 'to assess, judge'.

'uncensorious' was formed in Modern English by adding the negative prefix 'un-' to 'censorious'. 'Censorious' itself developed from Late Latin 'censoriosus' (from Latin 'cēnsor' and the verb 'censēre'), passed into Old/Middle French and Middle English before becoming the modern adjective 'censorious'.

Initially, the root sense (from Latin) related to judging or assessing; 'censorious' came to mean 'inclined to censure', and 'uncensorious' has meant 'not inclined to censure' — a meaning that has remained consistent.