τολμηρόν

From LSJ

τὸ δ' ἐξαίφνης τὸ ἐν ἀναισθήτῳ χρόνῳ διὰ μικρότητα ἐκστάν → suddenly refers to what has departed from its former condition in a time imperceptible because of its smallness

Source

Russian (Dvoretsky)

τολμηρόν: τό
1 дерзание, смелость Thuc.;
2 смелый поступок, подвиг Arst.