Akademik

до кончиков ногтей
ДО КОНЦА <ДО КОНЧИКОВ> НОГТЕЙ
[PrepP; these forms only; nonagreeing modif; fixed WO]
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(one is a certain type of person) entirely, in every way:
- (a [NP]) to the (one's) fingertips;
- every inch (a (the) [NP]);
- (a [NP]) to the core;
- (a [NP]) through and through.
     ♦ ...С такими людьми я ешё никогда не встречался, сразу видно: утончённый, изысканно-простой, до кончиков ногтей интеллигентный... (Катаев 3). ...Such people were quite beyond my ken. I saw at once that he was refined and yet exquisitely natural, an intellectual to the very fingertips (3a).

Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. . 2004.