křehkost znamená v angličtina

fragility [fragilities]▼(condition or quality of being fragile)
noun
[UK: frə.ˈdʒɪ.lɪ.ti] [US: frə.ˈdʒɪ.lə.ti]

frailty [frailties]▼(condition of being frail)
noun
[UK: ˈfreɪl.ti] [US: ˈfreɪl.ti]