Crossword clue: at right angles to the plane of the horizon or a base line
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
at right angles to the plane of the horizon or a base line
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Similar clues
the quality of being at right angles to a given line or plane (especially the plane of the horizon)
50% similar
→ perpendicularity