Definition of "love letter"

Thus, when he drew up instructions in lawyer language […] ; his clerks, however, understood him very well. If he had written a love letter, or a farce, or a ballade, or a story, no one, either clerks, or friends, or compositors, would have understood anything but a word here and a word there. For his signature, however, that was different.

1892, Walter Besant, “Prologue: Who is Edmund Gray?”, in The Ivory Gate […], New York, N.Y.: Harper & Brothers, […]

Now we are liberal with our innermost secrets, spraying them into the public ether with a generosity our forebears could not have imagined. Where we once sent love letters in a sealed envelope, or stuck photographs of our children in a family album, now such private material is despatched to servers and clouds operated by people we don't know and will never meet.

2013 June 14, Jonathan Freedland, “Obama's once hip brand is now tainted”, in The Guardian Weekly, volume 189, number 1, page 18

The film is both a tip of the chapeau to The New Yorker, among other American magazines, and a love letter to expat life in France. But beyond that? There isn't much going on beneath its extraordinary bejewelled surface.

2021 July 12, Nicholas Barber, “The French Dispatch: Four stars for Wes Anderson's latest”, in BBC‎

It was in this era, too, that author and Scotland the Brave songwriter Cliff Hanley penned The Glasgow Underground, a tongue-in-cheek love letter to the Subway in song.

2021 December 29, Conrad Landin, “Glasgow Subway: a city institution”, in RAIL, number 947, page 45

Dr Martin says the address the package has been sent to will likely get a "love letter" in the post from Customs.

2016 August 2, Nick Jarvis, “What Happens if You're Caught Getting Drugs in the Mail?”, in Vice‎