Able to be admitted or allowed; acceptable or worthy of being let in.
From Middle English and Latin admittere (ad- 'to' + mittere 'to send') plus -able, meaning 'capable of being.' The -able suffix comes from Latin -abilis, creating adjectives meaning 'able to be' or 'worthy of being.'
Admittable is a variant spelling of 'admissible,' but it's much older and rarer today. Most legal and formal contexts use admissible instead, showing how English sometimes retains multiple spellings from different historical periods before settling on one.
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