1.
[syn: altostratus, altostratus cloud]
The Collaborative International Dictionary of English v.0.48:
altostratus \altostratus\, Alto-stratus \Al`to-stra"tus\, n. [L.
altus high + L. & E. stratus.] (Meteor.)
A cloud formation similar to cirro-stratus, but heavier and
at a lower level; a stratus cloud at an intermediate altitude
of 2 or 3 miles.
[Webster 1913 Suppl. + WordNet 1.5]
WordNet (r) 3.0 (2006):
altostratus
n 1: a stratus cloud at an intermediate altitude of 2 or 3 miles
[syn: altostratus, altostratus cloud]