| Off-road motorcycle competition | 31 |
| Oklahoma city or writer Bagnold | 31 |
| One of Adam's grandchildren | 31 |
| One of Tennessee's twosomes | 31 |
| One billion years, in astronomy | 31 |
| One billion years, geologically | 31 |
| Org. with a Greenversation blog | 31 |
| Org. that monitors fuel economy | 31 |
| Org. that conducts many studies | 31 |
| Olympic pentathlete's blade | 31 |
| Omar of "House, M.D." | 31 |
| One of a joule's 10,000,000 | 31 |
| One dyne per centimeter measure | 31 |
| Oscar-winning composer Korngold | 31 |
| Oil company founder Halliburton | 31 |
| Orchestral premiere of 4/7/1805 | 31 |
| Olivia's leading man, often | 31 |
| Overcrowded U.S. hospital areas | 31 |
| Once, it meant "once" | 31 |
| Optical illusion artist M.C. -- | 31 |
| Outline of many a mountain road | 31 |
| Oil of wintergreen, for example | 31 |
| One who's not being precise | 31 |
| Opens up an on-line store, e.g. | 31 |
| Old world battleground, briefly | 31 |
| Of Earth's largest landmass | 31 |
| Odd number becomes the opposite | 31 |
| One of a lamb's parents ... | 31 |
| Oil family name of the '80s | 31 |
| One who can't go home again | 31 |
| One may be represented by stars | 31 |
| One-time Canadian major leaguer | 31 |
| Ophthalmologist's specialty | 31 |
| One concern of ophthalmologists | 31 |
| Org. governing overhead traffic | 31 |
| One who's more than devoted | 31 |
| Org. on "The X-Files" | 31 |
| Org. that fines for obscenities | 31 |
| Org. that oversees broadcasting | 31 |
| Org. that may call for a recall | 31 |
| One of the Big Three, for short | 31 |
| One may be red, white or silver | 31 |
| Orange children's character | 31 |
| One with a mister in Münster | 31 |
| Overdo the "what if?" | 31 |
| Often-welcomed part of the week | 31 |
| One of a Hawthorne title septet | 31 |
| Oxygen and helium, for instance | 31 |
| One might fight to the last one | 31 |
| One who needs to be rubbed out? | 31 |
| Order to curtail public bussing | 31 |
| One who commits grave offenses? | 31 |
| Organ in tadpoles but not frogs | 31 |
| One with a great view of a zoo? | 31 |
| One-third of a Elvis tune title | 31 |
| One-time David Bowie rock genre | 31 |
| One often found playing a round | 31 |
| One who's "toast" | 31 |
| One who writes about many cases | 31 |
| Old-fashioned "Neat!" | 31 |
| Old-fashioned "Cool!" | 31 |
| Overseer of govt. office bldgs. | 31 |
| Org. famous for selling cookies | 31 |
| Old inits. in telecommunication | 31 |
| One of two on a basketball team | 31 |
| One's conscience, hopefully | 31 |
| One of Islam's five pillars | 31 |
| Otto who split the uranium atom | 31 |
| Operation Uphold Democracy site | 31 |
| One of Yogi Bear's creators | 31 |
| One who's seen better times | 31 |
| Ozzy Osbourne's music style | 31 |
| One who might come into a house | 31 |
| Offenbach heroine and namesakes | 31 |
| Ones who can lift heavy weights | 31 |
| One getting by on chicken feed? | 31 |
| Opinion opposed to usual belief | 31 |
| One of a pair of towel markings | 31 |
| One may be found in the kitchen | 31 |
| One not out of the woods, maybe | 31 |
| Opening and closing facilitator | 31 |
| One who turns up in the garden? | 31 |
| One redefining the cutting edge | 31 |
| O'Hare, for United Airlines | 31 |
| Othello's villainous ensign | 31 |
| One sacred to ancient Egyptians | 31 |
| Opening action removing tension | 31 |
| Occupation before refrigerators | 31 |
| One might dangle from your neck | 31 |
| One with a pretty strong hunch? | 31 |
| Only Super Bowl won by the Jets | 31 |
| Off one's feed, so to speak | 31 |
| One who comes with a tied knot? | 31 |
| Ocean's shoreline incursion | 31 |
| Opposite of "persona" | 31 |
| Odysseus's rescuer, in myth | 31 |
| Onetime Justice Department div. | 31 |
| Opening musical bars, for short | 31 |
| One of Plato's 35 dialogues | 31 |
| Org. in "Odd Man Out" | 31 |