Green’s Dictionary of Slang

1. (US) something superlative [? it makes one draw a breath in awe].

1841		J. Mills Old Eng. Gentleman (1847) 354: ‘This is a breather,’ said Jack, wiping off the trickling perspiration from his features.
1866		R.B. Marcy Thirty Years of Army Life 370: This yere hill o’ yourn am a breather; ef it ain’t, d--n me.

2. (UK Und.) a lifetime; a life sentence.

1846

Swell’s Night Guide 68: She split on him for a crib-cracking fake, and they give it him for his breather. Aye, she lagged him for his life!

3. a lung.

1912

A.H. Lewis Apaches of N.Y. 87: She’d have put him hep to that bullet in his breather, mebby.

4. (N.Z.) exercise, designed to get one breathing hard.

1895		Mirror of Life 1 June 10/1: Corfield [...] had been undergoing his preparation at Leicester, where four-mile breathers [...] were daily indulged in.
1916		‘Anzac’ On the Anzac Trail 7: Our daily work began with the usual before-breakfast breather a brisk march over the hills, a spell of physical exercise, a pipe-opening ‘double,’ and then a free-and-easy tramp back to camp.
1919		Wodehouse ‘Leave It to Jeeves’ in My Man Jeeves [ebook] ‘The nurse takes the kid out ostensibly to get a breather, and they beat it down here’.

5. one who makes a phonecall, saying nothing and merely breathing, usu. for sexual pleasure, also attrib.

1977		(con. 1949) J.G. Dunne True Confessions (1979) 66: There were lots of clothes, actually, if you believed all the breathers calling in.
2004		J. Ellroy ‘Hot-Prowl Rape-O’ in Destination: Morgue! (2004) 312: I like to sniff toilet seats once in a blue moon [...] But basically I’m a specialist. I’m a note man and a breather.
2023		(con. 1962) J. Ellroy Enchanters 64: ‘[S]he says she’s been getting breather calls’.

6. the nose.

1957		Mad mag. Jan.–Feb. 21: Your repulsive breather, once repulsive and huge, / Caused people who saw it to run for refuge.
1971–2		C. Shafer ‘Catheads [...] and Cho-Cho Sticks’ in Abernethy Bounty of Texas (1990) 199: breather, n. – the nose.