wear something on one's sleeve

English

Etymology

This phrase may derive from a mediaeval custom at jousting matches. Knights are said to have worn the colours of the lady they were supporting, in cloths or ribbons tied to their arms.

The term does not date from that period though, and is first recorded in Shakespeare's Othello, 1604, in which the treacherous Iago's plan was to feign openness and vulnerability in order to appear faithful[1].

Verb

to wear something on one's sleeve

To express an emotion, belief, or stance overtly and make it an important part of one's public life.
- 2008 June 25, Neela Banerjee, “Religion and Its Role Are in Dispute at the Service Academies”, in New York Times‎:
  But religion is the one thing they encourage you to wear on your sleeve.
- 2008 June 28, Art Winslow, “Ethan Canin's "America, America"”, in Chicago Tribune‎, archived from the original on 2009-05-21:
  While he may wear his idealism and good-heartedness on his shirt sleeve, his passion is exuded more as an intellectualized than as a deeply felt quality. In modulating his voice, that is, Canin has chosen a character whose temperance might be admirable among the living but is less engaging when encountered in literature.

Related terms

to wear one's heart on one's sleeve

Translations

to habitually aggressively express a thought, attitude, or belief

Finnish: ilmaista avoimesti

References

c. 1603–1604, William Shakespeare, “The Tragedie of Othello, the Moore of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies: Published According to the True Originall Copies (First Folio), London: Printed by Isaac Iaggard, and Ed[ward] Blount, published 1623, OCLC 606515358, [Act 1, (please specify the scene number in lowercase Roman numerals)]:
:
Iago:
It is sure as you are Roderigo,
Were I the Moor, I would not be Iago:
In following him, I follow but myself;
Heaven is my judge, not I for love and duty,
But seeming so, for my peculiar end:
For when my outward action doth demonstrate
The native act and figure of my heart
In compliment extern, 'tis not long after
But I will wear my heart upon my sleeve
For daws to peck at: I am not what I am.

[1] . 1603–1604, William Shakespeare, “The Tragedie of Othello, the Moore of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies: Published According to the True Originall Copies (First Folio), London: Printed by Isaac Iaggard, and Ed[ward] Blount, published 1623, OCLC 606515358, [Act 1, (please specify the scene number in lowercase Roman numerals)]:
:
Iago:
It is sure as you are Roderigo,
Were I the Moor, I would not be Iago:
In following him, I follow but myself;
Heaven is my judge, not I for love and duty,
But seeming so, for my peculiar end:
For when my outward action doth demonstrate
The native act and figure of my heart
In compliment extern, 'tis not long after
But I will wear my heart upon my sleeve
For daws to peck at: I am not what I am.