1An ash tree native to eastern North America, Fraxinus americana, widely cultivated for its timber; (also) the strong, pale wood of this tree, now favoured especially for the manufacture of baseball bats (frequently attributive).
2Australian Any of various other trees thought to resemble the white ash, or producing similar timber, especially Eucalyptus fraxinoides (family Myrtaceae).
Late 16th century (in an earlier sense). From white + ash.
white ash/ˌwʌɪt ˈaʃ/
Refined sodium carbonate, prepared from black ash by washing with water followed by evaporation.
Mid 19th century. From white + ash.