Standard Lemma guide
Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.
Sound
Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.
No pronunciation record was provided for this word.
noun
A double-lens instrument for measuring slight variations of the Sun's diameter by photography, based on the common chord of two overlapping images.
Definition source: English Wiktionary via Wiktextract
Usage: historical
No example sentence was provided for this meaning.
Synonyms: none provided
Antonyms: none provided
History
From photo- + helio- + meter.
