From the second edition (1989):
(ɪndɪˈstɪŋkʃən) [f. in-3 + distinction, after indistinct.]

1. The fact of not distinguishing or making distinctions; failure to perceive or make a difference.

1624 Bp. R. Montagu Gagg 31 Such variety and difference is in traditions which this Hudler confoundeth to deceive his Novice with indistinctions. 1768 Woman of Honor II. 107 That scandalous indistinction between the worthy and the worthless. 1876 Stevenson Charles of Orleans Wks. 1894 II. 263 Was it always one woman? or are there a dozen here immortalised in cold indistinction?

2. The condition or fact of not being distinct or different; absence of distinguishing qualities or characteristics; undistinguishableness.

1644 Jessop Angel of Eph. 7 Sundry Divines‥doe prove the Identitie and Indistinction of Bishops and Presbyters both in name and Office in sacred Writ. 1654 Jer. Taylor Real Pres. 220 In a body there cannot be indistinction of parts, but each must possesse his own portion of parts. 1824 Lamb Elia Ser. ii. Blakesmoor in H——Shire, I was astonished at the indistinction of everything. Where had stood the great gates? What bounded the Court-yard? Whereabout did the outhouses commence?

3. Indistinctness, obscurity, dimness. Obs.

1651 Biggs New Disp. ⁋77 The indistinction, confusion and perpetuall turbulency of our Œconomy. 1693 South Twelve Serm. (1698) III. 62 His whole Soul is nothing but Night, and Confusion, Darkness, and Indistinction. a1774 Harte Charit. Mason (R.), Wild indistinction did their place supply; Half heard, half lost, th' imperfect accents die. 1795 Mason Ch. Mus. ii. 96 The numerous Composers who succeeded Tallis‥rather increased than diminished this indistinction of the words, by introducing more elaborate harmonies.

4. Absence of distinction or eminence; obscurity. nonce-use.

1865 Athenæum No. 1969. 105/1 Persons of distinction or in-distinction.