canoe, taboo, Tahoe etc.
Some four letter words with second letter U and fourth letter O are:autoeurojudokudoouzo
5 letter words with 2nd letter O and 4th letter N:boundcountcornydoingfoundgoinghoundjointloonymoundmountpointpoundroundsoundwoundyoung
vowel
Some five letter words with second letter O and fourth letter E are:bogeybowelbowercometcovencoverdowelhotellosermodelmowernoseynovelpowerrover
solar
Some four letter words with second letter U and fourth letter O are:autoeurojudokudoouzo
oblong
5 letter words with 2nd letter O and 4th letter N:boundcountcornydoingfoundgoinghoundjointloonymoundmountpointpoundroundsoundwoundyoung
vowel
Some five letter words with second letter O and fourth letter E are:bogeybowelbowercometcovencoverdowelhotellosermodelmowernoseynovelpowerrover
solar
pilot
Five letter words with the second and fourth letter O are:boronbosomcocoacoloncolordonorhonormoronmotorrobotrotor
Doona
sOuNd
Absorbent, cocoanuts, dinosaurs, floodgate and honorable are 9 letter words. The 4th letter is the letter o.
unto, undo, updo