turn a blind eye

Etymology
Probably from the idea of a person turning to look at something but not seeing it, as if their eyes are blind.

The term is frequently claimed  to originate from an incident during the First Battle of Copenhagen on 2 April 1801, when Vice Admiral Horatio Nelson (1758–1805) was ordered by Admiral Hyde Parker (1739–1807) through signal flags to discontinue naval action against a force of the Dano-Norwegian Navy. Nelson, who had been blinded in one eye early in his career, said to his flag captain Thomas Foley (1757–1833), “You know, Foley, I have only one eye—I have a right to be blind sometimes.” He then put his telescope to his blind eye and, remarking “I really do not see the signal,” continued the assault which ended in a British victory. However, this is not the source of the term as the  records uses dating to the 17th and 18th centuries.

Verb

 * 1)  To deliberately or knowingly ignore, overlook, or refuse to acknowledge something, especially when improper or unpleasant; to look the other way.

Usage notes
In early use, the term was often employed in conjunction with.

Translations

 * Catalan:
 * Chinese:
 * Mandarin:, , 睜一隻眼閉一隻眼
 * Cantonese: 隻眼開隻眼閉
 * Czech: přimhouřit oko
 * Dutch: door de vingers zien
 * Finnish: katsoa läpi sormien, katsoa vierestä, seurata katseella
 * French:
 * German: die Augen verschließen vor,, ,
 * Greek: κάνω τα στραβά μάτια
 * Hebrew:
 * Hungarian:
 * Icelandic: sjá í gegnum fingur við
 * Italian: chiudere un occhio
 * Japanese: 見て見ぬふりをする
 * Korean:, 모르는 척 하다
 * Macedonian:
 * Polish:, , przymknąć oko
 * Portuguese:
 * Romanian: închide ochii, se face că nu vede, se face că plouă
 * Russian:, закрыва́ть глаза́
 * Serbo-Croatian: progledati kroz prste ,
 * Spanish: hacer la vista gorda, hacerse de la vista gorda
 * Swedish:, , se mellan fingrarna
 * Thai:
 * Ukrainian: диви́тись крізь па́льці, закри́ти о́чі, заплю́щити о́чі