
1) Gothic architecture
Found on
https://www.crosswordclues.com/clue/lancet-window

A lancet window is a tall, narrow window with a pointed arch at its top. It acquired the `lancet` name from its resemblance to a lance. Instances of this architectural motif are typical of Gothic ecclesiastical structures of the earliest period. Lancet windows may occur singly, or paired under a single moulding, or grouped in an odd number with .....
Found on
http://en.wikipedia.org/wiki/Lancet_window

A tall, narrow window that terminates in a pointed apex.
Found on
http://www.artisansofthevalley.com/comm_gloss3.html

narrow, high window capped by a lancet, or acute, arch. The lancet arch is a variety of pointed arch in which each of the arcs, or curves, of the ...
Found on
http://www.britannica.com/eb/a-z/l/11

a tall, pointed window with no tracery
Found on
http://www.encyclo.co.uk/local/20559

long, narrow window with pointed head
Found on
http://www.encyclo.co.uk/local/22129

A Gothic pointed window.
Found on
http://www.encyclo.co.uk/local/22196

Window with a pointed arch
Found on
http://www.encyclo.co.uk/local/22203

In architecture, a lancet-window is a very long, straight, narrow window terminating in a peak or curve in the form of a lancet. Lancet-windows are almost peculiar to early English architecture, are found single, double or grouped three or five-fold according to their position within and requirements of the host building.
Found on
http://www.probertencyclopaedia.com/browse/TL.HTM

[
n] - a narrow window having a lancet arch and without tracery
Found on
http://www.webdictionary.co.uk/definition.php?query=lancet%20window

long, narrow window with pointed head
Found on
https://www.encyclo.co.uk/local/20402
noun a narrow window having a lancet arch and without tracery
Found on
https://www.encyclo.co.uk/local/20974

A narrow window with sharp pointed arches. Starting with Amiens, lancets were often subdivided into two and topped by a smaller rose window. Prior to this, lancets were typically surmounted by an oculus or round opening (fig.2, D; fig.4, D).
Found on
https://www.encyclo.co.uk/local/22199
No exact match found.