The compound willy-nilly, corresponding to Latin nolens volens, has acquired a meaning in American English that is absent in British English, namely the second of the senses in each of the following parts of the entry in the American Heritage Dictionary of the English Language (4th ed.):


1. Whether desired or not: After her boss fell sick, she willy-nilly found herself directing the project.
2. Without order or plan; haphazardly.
1. Being or occurring whether desired or not: willy-nilly cooperation.
2. Disordered; haphazard: willy-nilly zoning laws.
[Alteration of will ye (or he), nill ye (or he), be you (or he) willing, be you (or he) unwilling.]

Compare the above with the entry in the Oxford English Dictionary Online:

A. adv.
Whether it be with or against the will of the person or persons concerned; whether one likes it or not; willingly or unwillingly, nolens volens.

1608    T. Middleton Trick to catch Old-one i. sig. B,   Thou shalt trust mee spite of thy teeth, furnish me with some money, wille nille.
1797    E. Berkeley in G. M. Berkeley Poems Pref. p. ccxxix,   But her Ladyship would, willi nilhi, constantly join the one who drank the waters every morning, and converse with her.
1807    Salmagundi 25 Apr. 166   He was sure, willy nilly, to be drenched with a deluge of decoctions.
1818    J. Brown Psyche 121   From whence it follows, will y’ nill y’, The thought of your’s is mighty silly.
1884    A. Griffiths Chron. Newgate II. vii. 306   He?conceived an idea of carrying her off and marrying her willy nilly at Gretna Green.
1898    L. Stephen Stud. of Biographer II. vii. 272   You are engaged in the game willy-nilly, and cannot be a mere looker-on.
1. That is such, or that takes place, whether one will or no.

1877    Tennyson Harold v. i,   And someone saw thy willy-nilly nun Vying a tress against our golden fern.
1880    Cornhill Mag. Feb. 182   All willy-nilly spinsters went to the canine race to be consoled.
1882    Tennyson Promise of May ii. 119   If man be only A willy-nilly current of sensations.
2. erron. Undecided, shilly-shally.

1883    F. Galton Inquiries into Human Faculty 57   The willy-nilly disposition of the female in matters of love is as apparent in the butterfly as in the man.
1898    W. Besant Orange Girl ii. vi,   Let us have no more shilly shally, willy nilly talk.

When confronted with the semantic Americanism ‘haphazard (ly)’ from the AHD, the person who prompted this post, Jacobus (alias Pops), wrote to your humble blogger: “Could the dictionary be wrong? I was unaware of ‘willy nilly’ being used to mean ‘haphazard’ or ‘disoriented’.”

His query, it should be noted, is pure Goliadkin, the protagonist of Dostoevsky’s masterful fiction, The Double [Двойник]. To be convinced of the aptness of the identification, read this early novella and then see the nec plus ultra exegesis by Marianne Shapiro in Russian Literature, 56 (2004), 441-482 (revised version as ch. 2 in her book, The Sense of Form in Literature and Language, 2nd, exp. ed. [2009]).