The Collaborative International Dictionary of English v.0.48:

Aspen \Asp"en\ ([a^]s"p[e^]n), Asp \Asp\ ([.a]sp), n. [AS.
   [ae]sp, [ae]ps; akin to OHG. aspa, Icel. ["o]sp, Dan. [ae]sp,
   Sw. asp, D. esp, G. espe, [aum]spe, aspe; cf. Lettish apsa,
   Lith. apuszis.] (Bot.)
   One of several species of poplar bearing this name,
   especially the Populus tremula, so called from the
   trembling of its leaves, which move with the slightest
   impulse of the air.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Aspen \Asp"en\ ([a^]s"p[e^]n), a.
   Of or pertaining to the aspen, or resembling it; made of
   aspen wood.
   [1913 Webster]

         Nor aspen leaves confess the gentlest breeze. --Gay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

aspen
    n 1: any of several trees of the genus Populus having leaves on
         flattened stalks so that they flutter in the lightest wind

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "aspen":
   chattering, palsied, quaking, quavering, quavery, quivering,
   quivery, shaking, shaky, shivering, shivery, shuddering,
   succussatory, succussive, trembling, trembly, tremulous, vibrating,
   wobbly



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ASPEN
       Automatic System for Performance Evaluation of the Network


The Free On-line Dictionary of Computing (30 December 2018):

ASPEN

    A toy language for teaching compiler
   construction.

   ["ASPEN Language Specifications", T.R. Wilcox, SIGPLAN Notices
   12(11):70-87, Nov 1977].

   (1994-11-30)


U.S. Gazetteer Places (2000):

Aspen, CO -- U.S. city in Colorado
   Population (2000):    5914
   Housing Units (2000): 4354
   Land area (2000):     3.529800 sq. miles (9.142139 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    3.529800 sq. miles (9.142139 sq. km)
   FIPS code:            03620
   Located within:       Colorado (CO), FIPS 08
   Location:             39.192297 N, 106.824470 W
   ZIP Codes (1990):     81611
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Aspen, CO
    Aspen