Synonyms for Horizon (same or very similar meaning)
WordNet sense 1 (the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth):
celestial horizon
WordNet sense 2 (the line at which the sky and Earth appear to meet):
skyline, apparent horizon, sensible horizon, visible horizon
WordNet sense 3 (the range of interest or activity that can be anticipated):
purview, view
From the ODE community, based on WordNet
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