| Oriole great Ripken | 19 |
| Oriole color | 12 |
| Oriole catcher: 1955–62 | 30 |
| Oriole : Maryland :: __ : Hawaii | 32 |
| Orinoco, por ejemplo | 20 |
| Orinoco, e.g. | 13 |
| Orinoco y Guadalquivir | 22 |
| Orinoco tributary | 17 |
| Orinoco shocker | 15 |
| Orinoco makeup | 14 |
| Orinoco Flow singer | 22 |
| Orinoco flow | 12 |
| Orinoco feeder | 14 |
| Orinoco contents | 16 |
| Origins of earthquakes | 22 |
| Origins of all people, partially | 32 |
| Origins of a phoenix | 20 |
| Origins Game Fair, e.g. | 23 |
| Origins | 7 |
| Originators of putt-putts | 25 |
| Originators | 11 |
| Originator of the phrase "truth is stranger than fiction" | 67 |
| Originator of the phrase "Pandora's box" | 54 |
| Originator of the phrase "Let the punishment fit the offense" | 71 |
| Originator of the phrase "Familiarity breeds contempt" | 64 |
| Originator of the phlogiston theory | 35 |
| Originator of the occasion celebrated on this date | 50 |
| Originator of the maxim "One swallow does not make a summer" | 70 |
| Originator of the formula e^ix = cos x + i sin x | 48 |
| Originator of the equation e to the power (pi i) + 1 = 0 | 57 |
| Originator of political animals | 31 |
| Originator of Jellicle Cats | 27 |
| Originator of Eur. Common Market | 32 |
| Originator of euphuism | 22 |
| Originator of cutout dresses | 28 |
| Originator of a popular peanut butter cup | 41 |
| Originator of "The Weakest Link" | 42 |
| Originator | 10 |
| Originative | 11 |
| Origination point for many fireworks | 36 |
| Origination point | 17 |
| Origination of first life on earth | 34 |
| Origination | 11 |
| Originating within a company | 28 |
| Originating in the sea | 22 |
| Originating in the intellect | 28 |
| Originating from within | 23 |
| Originates (from) | 17 |
| Originates | 10 |
| Originated at | 13 |
| Originated a word | 17 |
| Originated (from) | 17 |
| Originated | 10 |
| Originate, so to speak | 22 |
| Originate, as a trail | 21 |
| Originate, as a river | 21 |
| Originate, as a phrase | 22 |
| Originate from | 14 |
| Originate (hint #3) | 19 |
| Originate (from) | 16 |
| Originate | 9 |
| Originals | 9 |
| Originally, the greatest extent of the Ottoman Empire | 53 |
| Originally, once | 16 |
| Originally, a male servant | 26 |
| Originally, a choral song | 25 |
| Originally, a castle-wall slit | 30 |
| Originally went by | 18 |
| Originally positioned | 21 |
| Originally named: Fr. | 21 |
| Originally named | 16 |
| Originally known as | 19 |
| Originally called | 17 |
| Originally "The Village Virus" | 40 |
| Originally "The Sea-Cook" | 35 |
| Originally "The Lost Generation" | 42 |
| Originally "Mag's Diversions" | 43 |
| Originally "Incident at West Egg" | 43 |
| Originally "Ba! Ba! Black Sheep" | 42 |
| Originally | 10 |
| Original: Prefix | 16 |
| Original-sin site | 17 |
| Original, to Orff | 17 |
| Original, in Ostia | 18 |
| Original, in Germany | 20 |
| Original, at Oktoberfest | 24 |
| Original, as settings | 21 |
| Original _____ | 14 |
| Original ___ album | 18 |
| Original ___ | 12 |
| Original words | 14 |
| Original word forms | 19 |
| Original word form | 18 |
| Original Woodstock rocker | 25 |
| Original woman | 14 |
| Original U.S.S. Enterprise helmsman | 35 |
| Original U.S. space station | 27 |
| Original U.K. "Whose Line Is It Anyway?" host Anderson | 64 |
| Original Trivial Pursuit edition | 32 |
| Original title: "TheVarious Arms" | 43 |