What is "the other day"

Other \Oth"er\, pron. & a. [AS. [=o][eth]er; akin to OS. [=a][eth]ar, [=o][eth]ar, D. & G. ander, OHG. andar, Icel. annarr, Sw. annan, Dan. anden, Goth. an[thorn]ar, Skr. antara: cf. L. alter; all orig. comparatives: cf. Skr. anya other. [root]180. Cf. Alter.] Usage: [Formerly other was used both as singular and plural.]

1. Different from that which, or the one who, has been specified; not the same; not identical; additional; second of two.

   Each of them made other for to win.
   --Chaucer.

   Whosoever shall smite thee on thy right cheek, turn to him the other also.
   --Matt. v. 39.

2. Not this, but the contrary; opposite; as, the other side of a river.

3. Alternate; second; -- used esp. in connection with every; as, every other day, that is, each alternate day, every second day.

4. Left, as opposed to right. [Obs.]

   A distaff in her other hand she had.
   --Spenser.

   Note: Other is a correlative adjective, or adjective pronoun, often in contrast with one, some, that, this, etc.

   The one shall be taken, and the other left.
   --Matt. xxiv. 41.

   And some fell among thorns . . . but other fell into good ground.
   --Matt. xiii. 7, 8. It is also used, by ellipsis, with a noun, expressed or understood.

   To write this, or to design the other.
   --Dryden. It is written with the indefinite article as one word, another; is used with each, indicating a reciprocal action or relation; and is employed absolutely, or eliptically for other thing, or other person, in which case it may have a plural.

   The fool and the brutish person perish, and leave their wealth to others.
   --Ps. xlix. 10.

   If he is trimming, others are true.
   --Thackeray. Other is sometimes followed by but, beside, or besides; but oftener by than.

   No other but such a one as he.
   --Coleridge.

   Other lords beside thee have had dominion over us.
   --Is. xxvi. 13.

   For other foundation can no man lay than that is laid.
   --1 Cor. iii. 11.

   The whole seven years of . . . ignominy had been little other than a preparation for this very hour.
   --Hawthorne.

   Other some, some others. [Obs. or Prov. Eng.]

   The other day, at a certain time past, not distant, but indefinite; not long ago; recently; rarely, the third day past.

   Bind my hair up: as 't was yesterday? No, nor t' other day.
   --B. Jonson.

adv. (context idiomatic English) recently; lately; a few days ago.