An aspen is a tall tree with leaves that move a lot in the wind.
aspen in British English
(ˈæspən)
noun
1.
any of several trees of the salicaceous genus Populus, such as P. tremula of Europe, in which the leaves are attached to the stem by long flattened stalks so that they quiver in the wind
Archaic name: asp
adjective
2. archaic, mainly literary
trembling
Word origin
Old English æspe; see asp2
Aspen in American English
(ˈæspən)
city in central Colorado: ski resort: pop. 5,000
aspen in American English
(ˈæspən)
noun
1.
any of several kinds of poplar tree (genus Populus) with flattened leafstalks that cause the leaves to flutter in the least breeze
adjective
2.
of or like an aspen
Word origin
ME aspe (aspen, in comp.) < OE æspe < IE base *apsa > Lith ãpuš, OPrus abse