These are three-letter words that do not extend 2-letter words.
AZO j containing nitrogen COZ n short for cousin (also CUZ) FEZ FIX FIZ v to make a hissing or sputtering sound (also FIZZ) JEE v of horses, to urge on (also GEE) JEU n a game (pl. JEUX) JEW v to cheat or get the better of (not in OSPD3) JIB v to refuse to proceed further JIG JUG LEZ n a lesbian (not in OSPD3) LUX n a unit of illumination NIX v to veto or cancel PYX v to test QUA p in the capacity of RAJ n sovereignty SUQ n a marketplace (also SUK, SOUK) TUX n short for tuxedo, a dinner jacket WIZ n a very skilful person ZAP ZEE n Amer. form of zed ZEK n an inmate of a labour camp in the former USSR ZIG v same as ZAG, above ZIP ZOA n a plural of zoon, a unified individual creature ZOO
AUK AVA AVE AVO DAK EKE EVE GUV ICK ILK IRK IVY KEA KEG KEP KEY KIP KIR KOA KOB KOI KUE LEK LEV LUV OAK OKE OVA SKI SKY TSK UKE VAC VAU VAV VEE VEG VIA VIE VIG VIM VUG YUK
AFF AFT BUY CRY CWM DRY FEE FEU FEW FEY FIB FIE FIG FIL FIR FLU FLY FOB FOG FOU FRO FRY FUB FUD FUG FUR GEY GUY GYM GYP HUB HUE HUG HYP ICH ICY LEY NTH OAF PHT PLY PRY SEW SLY SPY STY SYN TEW THY TRY TWA UGH WAP WHY WIG WRY WUD WYN YIP
ACE ACT APT BRA BRO BRR BUB BUD BUG BUR CAP CEE CEP COB COG COL COO COT CUB CUD CUE CUR DAP DIB DIM DIP DUB EBB ECU GAP GIB GIP ICE IMP NIB NIM NIP OCA POI POL POT PRO PUB PUD PUG PUL PUR RAP RIB RIM RIP ROB ROC RUB SAC SAP SEC SUB TUB URB
DIE DIG DUD DUE DUG DUI DUO EAU EGG GEE GIE GIG GUL ILL LEA LEE LEG LEI LEU LUG NIL OIL OLD OLE OOT OUD OUR RIA RIG ROT RUE RUG SAU SEA SEE SEG SEI SRI SUE TEA TEE TEG TUG TUI ULU URD URN