- BAR, FUR, IRK, ONE, ROT, SHE, VEX
ROT is the odd-one-out - all other words form another real word in English (in fact, one of the other words in the list) when encrypted with a Caesar shift of 13 letters (known as rot-13):
ONE, SHE, VEX, BAR, EBG, FUR, IRK
- CZT, FIR, FOU, OCH, PED, QUA, VIE
OCH is the odd-one-out - all other words comprise the first 3 letters of a word translating as '4' in a European language:
CZT(ERY) (Polish), FIR(E) (Norwegian), FOU(R) (English), OCH(O) (8 in Spanish), PED(WAR) (Welsh), QUA(TRE) (French), VIE(R) (German)
(QUA(TRO) in Portuguese and QUA(TTRO) in Italian are among other possibilities for this answer...)
- CAR, HIS, LIE, RAY, ROT, TAN, WAR
WAR is the odd-one-out - all other words appear as substrings in codewords in the NATO phonetic alphabet:
(OS)CAR, (W)HIS(KEY), (JU)LIE(TT), (X)RAY, (FOXT)ROT, TAN(GO), WAR