Wiktionary
n. (context US English) A raised platform on the roof of a house, especially one on a coastal house originally used for viewing the arrival of shipping
WordNet
n. a lookout atop a coastal house
Wikipedia
A widow's walk also known as a "widow's watch" (or roofwalk) is a railed rooftop platform often with a small enclosed cupola frequently found on 19th-century North American coastal houses. The name is said to come from the wives of mariners, who would watch for their spouses' return, often in vain as the ocean took the lives of the mariners, leaving the women widows. In other coastal communities, the platforms were called Captain's Walk, as they topped the homes of the more successful captains; supposedly, ship owners and captains would use them to search the horizon for ships due in port.
However, there is little or no evidence that widow's walks were intended or regularly used to observe shipping. Widow's walks are in fact a standard decorative feature of Italianate architecture, which was very popular during the height of the Age of Sail in many North American coastal communities. The widow's walk is a variation of the Italianate cupola. The Italianate cupola, also known as a "belvedere", was an important ornate finish to this style, although it was often high maintenance and prone to leaks.
Image:Widows Walk Gaithersburg.jpg|alt=The roof of a house with a widow's walk on top, consisting of a small room surrounded by railing|A widow's walk in Gaithersburg, Maryland. Walk.jpg|A widow's walk on a home overlooking a harbor in Massachusetts. "widow's watch" on a home in Saint John, New Brunswick, Canada. Unlike examples in warmer climates, this one is enclosed.
Beyond their use as viewing platforms, they are frequently built around the chimney of the residence, thus creating access to the structure. This allows the residents of the home to pour sand down burning chimneys in the event of a chimney fire in the hope of preventing the house from burning down.
Widow's Walk ( 2002) is a detective novel by American crime writer Robert B. Parker, the 29th in his Spenser series.
Usage examples of "widow's walk".
There was a long winding drive up a hill, and after a sharp turn, there was a pretty Victorian with a wide porch and widow's walk.
It was Julie who stood up first to face the odd old house with the roof almost like a widow's walk and the front door missing.
For a moment, as I readjusted to the darkness, I thought I saw a long row of women standing on the widow's walk and pointing my way.
Outside, running east and west along the crest of two gables leading from the belfry, a narrow widow's walk was set off by an intricate wrought-iron railing.
They passed under an archway with a sign overhead that read THE WIDOW'S WALK.