Attentive; paying close attention; intent on something.
From Latin 'attentus' (stretched toward, attentive), past participle of 'attendere' (to stretch toward). This archaic English adjective directly borrowed the Latin form.
Shakespeare used 'attent' in Hamlet ('the attent'st ear')—it's wonderfully economical, doing in one syllable what 'attentive' needs three for, yet it sounds almost alien to modern ears.
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