compound words that begin with letter O?
92992
overseas\nouterbounds\nunderscore\nundereasy\noverdone
900102
Uno, dos, tres, cuatro, cinco, seis, siete, nueve, diez, once, doce, trece, catorce, quince, dieciséis, diecisiete, dieciocho, diecinueve, veinte
665466
none of the above.  Self-evident is the closest, but that isn't really a compound word, it's a hyphenated word.
808693
ZIP\nZIPPY\nZIPS\nZIRAM\nZIT\nZITI\nZITIS\nZITS\nZIZIT\nZLOTE\nZLOTY\nZOA\nZOEA\nZOEAE\nZOEAL\nZOEAS\nZOIC\nZOMBI\nZONAL\nZONE\nZONED\nZONER\nZONES\nZONK\nZONKS\nZOO\nZOOID\nZOOKS\nZOOM\nZOOMS\nZOON\nZOONS\nZOOS\nZOOTY\nZORI\nZORIL\nZOWIE\nZYME\nZYMES
1020431
aso - dog\naso - usok\n\npuno - tree\npuno - full
157207
bcos that is the starting of a second word
1186529
Try making up your own word or go to http://www3.merriam-webster.com/opendictionary/ or try http://www.merriam-webster.com/\n\nGood luck.
391700
I came up with 80 words (not including 1 and 2 letter words) before I got tired of looking. Here's my list.\n\nAir,art,ate,act,are,arc,ace,\ncat,car,eat,ear,hot,her,hit,\nhoe,hat,hie,ice,ire,kit,ore,\noar,rat,roe,rot,tar,tea,toe,\nthe,arch,char,cart,core,cake,\ncote,chat,coat,care,cork,each,\nhear,heat,hart,hike,hire,hare,\nhair,hate,itch,okra,rich,rack,\nrote,rice,race,rate,tear,trek,\ntake,tack,tore,tick,tire,tier,\nchoke,cheat,chore,croak,chart,\nchair,cater,crate,earth,heart,\nreach,roach,track,teach,torch,\ntrick
500967
Water.\n\nIt is the letter H to O, or H2O.
639621
Here's some longer words you can make from tolerance:\n\ncarotene\nelectron\nrelocate\nacetone\ncentral\ncleaner\ncorneal\nelector\neternal\nlectern\nreenact\ntreacle\nantler\ncanter\ncantor\ncareen\ncartel\ncarton\ncenter\ncereal\nclaret\ncornea\ncornet\ncreate\ncreole\nencore\nlancer\nlancet\nlearnt\nloaner\nlocate\nnectar\noctane\noracle\nornate\nrecant\nrecent\nrectal\nrelate\nrelent\nrental\ntrance\n\nI could give you more, but it might be overkill
370858
"other"\nAny word --> Any other word
710886
birth\nburst\nearly\nearnest\nfurther\nheard\nheart\nlearn\noperator\npartner\nperfect\npurpose\nsailor\nsearch\nserve\nshower\nthirst\nurge\nurgent\nworth
409349
CABBAGE\n\n\nCAB\nABBA\nBAG\nAGE
83413
NO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO\nNoNO
859666
Uk- N\nHolland-O\nNorway-T
768317
The letter o is a number
904915
Try "ornery" or "odd"\n\nNRT