Incomplete or unfinished; lacking completion or maturity.
From Greek 'ateles' (incomplete) + the suffix '-ene' (a chemistry/geology suffix sometimes used as an adjective ending), though this word is quite rare in modern usage and may be archaic or technical.
This is one of those beautiful but forgotten words that shows how English borrowed Greek fragments and tried to make them work as everyday adjectives—it's like fossils of scientific vocabulary from centuries past.
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