To collapse or fall into or as if into a faint.傾覆或倒下，狀如暈倒
柯林斯高階英漢雙解學習詞典釋義
N-COUNT
（船的）龍骨
The keel of a boat is the long, specially shaped piece of wood or steel along the bottom of it.
PHRASE
平穩進行；順順當當
If you say that someone or something is on an even keel, you mean that they are working or progressing smoothly and steadily, without any sudden changes.
例句
Jason had helped him out with a series of loans, until he could get back on an even keel.賈森接連借了幾筆錢給他，在他重新走上正軌之前幫他渡過了難關。
英漢詞典釋義
n.
(船的)龍骨
The side of a ship flares from the keel to the deck.船舷從龍骨向甲板外傾。
vt. & vi.
翻身;傾覆
The boat keeled over in the strong winds.船在大風中翻了。
英英詞典釋義
Noun
1. the median ridge on the breastbone of birds that fly
2. one of the main longitudinal beams (or plates) of the hull of a vessel; can extend vertically into the water to provide lateral stability