A HORIZON

 I. (noun) 

Sense 1

Meaning:

The top layer of a soil profile; usually contains humus

Synonyms:

A-horizon; A horizon

Classified under:

Nouns denoting spatial position

Instance hypernyms:

soil horizon (a layer in a soil profile)

Meronyms (substance of "A horizon"):

humus (partially decomposed organic matter; the organic component of soil)

Credits