From WordNet (r) 3.0 (2006) [wn]:
A-line
n 1: women's clothing that has a fitted top and a flared skirt
that is widest at the hemline; "it is called the A-line
because the effect resembles the capital letter A"
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Aline \A*line"\, v. t.
To range or place in a line; to bring into line; to align.
--Evelyn.
[1913 Webster]