unaccountably /BrE ʌnəˈkaʊntəbli 
, AmE ˌənəˈkaʊn(t)əbli /
adverb
[vanish, appear, late, absent] inexplicablement
quite unaccountably,… sans qu'on sache pourquoi,…
unaccountably
English → French
Oxford English–FrenchEnglish → FrenchOxford English–French