Meaning of 'sunlines'
He was a man of perhaps forty five, and his face was thick featured, phlegmatic, with sunlines around small light eyes — the face of a deliberate man.
Nightmare Town Stories By Dashiell Hammett
What is sunlines? Is it a wrinkle made by sunlight or something?
This word can't be found anywhere in dictionary or elsewhere.
Solution 1:
A review of Nightmare Town by Mat Brewster on the BlogCritics website reports that the collection consisted of stories that were at least 70 years old at the time of its release (1999), which would put the date of occurrence of Hammett's use of the word sunlines at not later than 1929.
A Google Books search for sun line, sunline, sun lines, and sunlines turns up only three relevant matches from the period 1900–1940; but one of them seems to explain the intended meaning of the term. From Cynthia Stockley, Virginia of the Rhodesians (1913) [combined snippets]:
Mrs. Skeffy told me confidentially one morning while she was massaging the marks under her eyes—which she called sun-lines and I called crow's-feet—that she thought Mr. Waybrant was the cleverest man she had ever met.
From one year earlier we have this from Pearl Franklin Godfrey, "Faithless Husbands: A Story," in The Craftsman (May 1912):
Silas looked like a man who had driven a slow horse all his life and waited at the bars for cows—men who do that get to have the look. A bit of light-colored hair that was old enough to be white, straggled out from beneath a battered straw hat, over his sun-burned face. When Dart came upon him he was holding between his knees an old fish pole while he took a new line from a piece of store paper. He did not raise his eyes for a minute or two, then there was a gleam of triumph amid the wrinkles and sun lines of the old Yankee face—a half smile that puckered up his features just as it had when he was a boy.
And finally, from Kate Jordan, The Next Corner (1921), we have this:
A look into the mirror of her vanity case brought a wondering, half-amused shrug. How she had gibed at his criticism—and behold!—it had borne fruit, for her face was but lightly touched with the pencils and powders. Of course he had been right. The habit of plastering oneself into a Pierrot can grow into a sort of debauch without one's realizing it. She had a sense of his approval while she pictured him leaning on a deck rail, smoking a pipe, the droll, little sun lines showing about his eyes.
Evidently, in the 1910s and 1920s—and perhaps later—the word sunlines (or sun-lines or sun lines) referred to lines or wrinkles near a person's eyes, marks that many people today call crow's-feet.
Solution 2:
Simple answer:
"Sun lines" are wrinkles (typically around the eyes), caused by the sun.
It is not a common word, but here it is referenced from a newspaper ad circa 1935. Also mentioned in the same ad are "squint lines", so the two terms look interchangeable.
Solution 3:
Facial [Sun]lines and wrinkles (rhytides) form because of the following factors:
• Ageing processes • Sun damage • Muscle movement • Gravity • Injury • Surgery • Acne • Other skin diseases with a tendency to scar (e.g. discoid lupus)
See DermNet NZ Link
Additionally, I found a nautical reference at the following Link
- Plot — Graphical facilities To draw a 2 pixel wide black line with 50% opacity one hour after the beginning of the nautical morning twilight, the sunlines parameter would look like this: [graph]
Ngram & Google books:
An Ngram query of “sunlines” Link returned many references to books on a variety of topics, including the Dashiell Hammett novel which occasioned your OP.
WARNING: The dermatological answer is merely semi-educated guess as I, too, could find no direct dictionary reference to "sunlines" other than in the dermatological & nautical contexts. Note: even the spell-check wants to correct or replace this word.