The term 'CERTAIN ERRATUM' is a combination of two words, 'CERTAIN' and 'ERRATUM'. 'CERTAIN' is an adjective meaning 'DEFINITE' or 'SURE', while 'ERRATUM' is a noun meaning 'an error in printing or writing'. Together, the term refers to an error that is DEFINITE or SURE. The crossword solution for this term is 'OMISSION', which is a noun meaning 'the act of omitting or leaving out'. Therefore, the term 'CERTAIN ERRATUM' can be defined as an error that is DEFINITE or SURE, usually caused by leaving something out.