Etymology 2
Sino-Vietnamese word from 補 (“to supplement”).
Adjective
bổ
- (of food, drink or nutritional supplements, compatible with following Sino-Vietnamese elements) healthy; wholesome
- thuốc bổ ― a nutritional supplement
- bổ phổi/phế ― good for one's lungs
- bổ máu/huyết ― good for one's blood
- (of activities) vô bổ ― unhelpful; unproductive
Etymology 3
See vỗ. This is a form that did not undergo lenition.
Verb
bổ
- (obsolete) Southern Vietnam form of vỗ
1895, Huình Tịnh Của, Đại Nam Quấc âm tự vị:滇 Xan. n.
[…]
Sóng ― sóng bổ, sóng đánh.- 滇 Xan. n.
[…]
Sóng ― the waves hitting the shore.
1909, Nguyễn Liên Phong, “Bà-Rịa”, in Nam Kỳ phong tục nhơn vật diễn ca:Làng Phước-hãi, lưới bạc muôn, Ở theo mé biển tuy buồn mà vui.
Buồn nghe sóng bỗ từ hồi, Vui vì đông đão tới lui chĩnh tề.- At the village of Phước-hãi, [although] the nets are always silvery [due to the reflection from fishscales], living by the sea has its ups and downs.
The repetitive sound of the waves hitting the shore brings you down, [but] the constant throngs of people coming and leaving lifts you up.