| The wide blue yonder | 20 |
| Pre-Novocain stuff | 18 |
| Outer space | 11 |
| Outdated anesthetic | 19 |
| Onetime anesthetic | 18 |
| Old sleep aid? | 14 |
| Old knockout agent | 18 |
| Number no longer used | 21 |
| Novocain predecessor | 20 |
| Knockout gas | 12 |
| Kin of chloroform | 17 |
| It's a real knockout | 24 |
| It can put you out | 18 |
| Flammable anesthetic | 20 |
| Empyrean | 8 |
| Early number? | 13 |
| Early anesthesia | 16 |
| Cousin of chloroform | 20 |
| Cosmos | 6 |
| Chloroform substitute | 21 |
| Aristotle's "fifth element" | 41 |
| Air beyond the clouds | 21 |
| A great composer? | 17 |
| Who "In the ___" | 26 |
| What a knockout! | 16 |
| Welsh alt-rock band | 19 |
| Upper regions of space, poetically | 34 |
| Upper regions of space, figuratively | 36 |
| Upper reaches of space | 22 |
| Upper places in space | 21 |
| This could put you under | 24 |
| There was a time it could knock you out | 39 |
| The far-blue yonder | 19 |
| Space, to poets | 15 |
| Space out yonder | 16 |
| Solvent for resins and fats | 27 |
| Rarefied air | 12 |
| Rare air | 8 |
| Preparation for drilling? | 25 |
| Preoperative delivery, once | 27 |
| Potent anesthetic | 17 |
| Passé gas | 12 |
| Passé anesthetic | 19 |
| Part of the gasoline additive M.T.B.E. | 38 |
| Outmoded anesthetic | 19 |
| Outer regions of space | 22 |
| Outer region of space | 21 |
| Out-of-use anesthetic | 21 |
| Onetime dental anesthetic | 25 |
| One-time labratory solvent | 26 |
| One-time anesthetic | 19 |
| One on it may be out of it | 26 |
| Old-timey anesthetic [need a holiday gift? avxwords.com annual subscriptions are just $15] | 90 |
| Old-time knockout gas | 21 |
| Old-time knockout | 17 |
| Old-fashioned anesthetic | 24 |
| Old under-taker | 15 |
| Old surgery aid | 15 |
| Old sleeping aid? | 17 |
| Old pre-op inhalant | 19 |
| Old number | 10 |
| Old knockout fumes | 18 |
| Old knockout cause | 18 |
| Old hospital supply | 19 |
| Old hospital administration | 27 |
| Old anaesthetic | 15 |
| Number that's no longer used | 32 |
| Number that might be used when counting backward from 100? | 58 |
| Number no longer used? | 22 |
| Nitrous oxide predecessor | 25 |
| Laughing-gas kin | 16 |
| Knockout number? | 16 |
| Knockout choice, once | 21 |
| Knock-out gas, once | 19 |
| It's a gas? | 15 |
| It puts people out | 18 |
| It put people to sleep, once | 28 |
| It could knock you out | 22 |
| It can knock people out | 23 |
| Inhaled anesthetic of old | 25 |
| Inhalation anesthetic of old | 28 |
| Inhalant anesthetic of the past | 31 |
| Former number? | 14 |
| Flammable liquid | 16 |
| Fifth element, per Aristotle | 28 |
| Fifth classical element | 23 |
| Ethyl oxide | 11 |
| Early surgery aid | 17 |
| Dr. Morton's anesthetic | 27 |
| Dr. Larch's drug in "The Cider House Rules" | 57 |
| Discovery of a Spanish chemist in 1275 | 38 |
| Dioxane, e.g. | 13 |
| Dimethyl ___ (aerosol propellant) | 33 |
| Dentist's supply, once | 26 |
| Dentist's gas | 17 |
| Dental anesthetic of old | 24 |
| Composition of outer space, in old belief | 41 |
| Colorless liquid | 16 |
| Clear blue sky | 14 |
| Chloroform's predecessor | 28 |