Wordnet Synset 05137667-n

http://lila-erc.eu/data/lexicalResources/LatinWordNet/id/LexicalConcept/05137667-n an entity of type: LexicalConcept

the shortest distance that permits radio signals (of a given frequency) to travel from the transmitter to the receiver by reflection from the ionosphere
Wordnet Synset 05137667-n 

data from the linked data cloud