Sentence:  About once a year, and generally after the six o'clock news (query for B.B.C. experts — is the six o'clock public more gullible?) a Very Big Noise has reported that, after the n — nth or n — plus — <WSD>oneth</WSD> year of the war, the health of the nation  is yet again better than ever. 
Meaning of the word marked with <WSD> tags:  ( Used at the end of algebraic expressions indicating ordinal position that end in 1, such as (k+1)th)