| In order | 8 |
| In orbit | 8 |
| In or out trailer | 17 |
| In optimum conditions | 21 |
| In optimum acceleration mode | 28 |
| In opposition, to Keats | 23 |
| In opposition to, with "of" | 37 |
| In opposition to one another | 28 |
| In opposition to | 16 |
| In opposition | 13 |
| In opposite order | 17 |
| In operation | 12 |
| In open sight | 13 |
| In open court | 13 |
| In oneÂ’s Sunday best | 24 |
| In one's _____ eye | 22 |
| In one's ___ (drunk) | 24 |
| In one's ___ | 16 |
| In one's tree? | 18 |
| In one's Sunday finest | 26 |
| In one's Sunday best | 24 |
| In one's spare time | 23 |
| In one's solitude | 21 |
| In one's slip? | 18 |
| In one's senses | 19 |
| In one's second childhood | 29 |
| In one's salad days | 23 |
| In one's right mind | 23 |
| In one's prime? | 19 |
| In one's prime | 18 |
| In one's own residence | 26 |
| In one's office | 19 |
| In one's natural state | 26 |
| In one's mind | 17 |
| In one's maturity | 21 |
| In one's majority; mature | 29 |
| In one's interest | 21 |
| In one's hometown | 21 |
| In one's heart of hearts | 28 |
| In one's head, as opposed to on paper | 41 |
| In one's face | 17 |
| In one's element | 20 |
| In one's dotage | 19 |
| In one's dossier | 20 |
| In one's cups | 17 |
| In one's bunk | 17 |
| In one's birthday suit | 26 |
| In one's bare feet | 22 |
| In one's arms | 17 |
| In one's abode | 18 |
| In one's "birthday suit" | 38 |
| In one ___ out the other | 24 |
| In one year and out the other? | 30 |
| In one year and out the other | 29 |
| In one word, "I told you so!" | 39 |
| In one way, these make sense | 28 |
| In one way or another | 21 |
| In one sitting | 14 |
| In one session | 14 |
| In one sense, it's used in breaking, and in another, in entering | 68 |
| In one piece | 12 |
| In one large mob | 16 |
| In one group | 12 |
| In one fell swoop | 17 |
| In one end and out the other, for short | 39 |
| In one end and out the other, briefly | 37 |
| In one end and out the other | 28 |
| In once more | 12 |
| In on, with "to" | 26 |
| In on, with ''to'' | 34 |
| In on, slangily | 15 |
| In on, like a cool cat | 22 |
| In on the latest trends | 23 |
| In on the crime | 15 |
| In on something | 15 |
| In on | 5 |
| In olden times | 14 |
| In olden time | 13 |
| In olden days | 13 |
| In olde times | 13 |
| In old show biz, he was no dummy | 32 |
| In office | 9 |
| In ocean waters | 15 |
| In NYC, Madison or Lexington | 28 |
| In now | 6 |
| In nothing flat | 15 |
| In not too long, old-style | 26 |
| In Norse myth king of the Huns | 31 |
| In normal seasons, only month when the NBA, MLB, NHL and NFL all have scheduled games | 85 |
| In noisy confusion | 18 |
| In no way new | 13 |
| In no way mod | 13 |
| In no way | 9 |
| In no uncertain terms | 21 |
| In no time ____: instantly | 26 |
| In no time ____ (instantly) | 27 |
| In no time ___ (instantly) | 26 |
| In no time | 10 |
| In no specific place | 20 |
| In no particular order | 22 |