Wiki....
"In 1841, the bay was used as a base by pirates and caused serious concern to foreign merchant ships trading with China. The pirates were subsequently repulsed by the British Fleet; hence the name. Another theory holds that the bay was named after HMS Repulse which was stationed at the bay at one point."
From A Dictionary of Modern American Usage by Bryan A. Garner:
Repulse is primarily physical<after repeated warnings, he was repulsed from the premises>; repel is primarily figurative<the body odors on the subway repelled her>.
The cry was "repel boarders", not "repulse boarders". I suspect that Wiki was conjecture by an American rather than an English speaker.
I remember that when (the British jazz musician) Ronnie Scott came to HK, he was interviewed on the radio and asked how he liked it here. He said, "It's all right once you get used to playing sideways."
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I remember the White Russians who used to live in Tsim Sha Tsui. I was aware of some old men in dark, baggy suits, but there must have been some women too. As I understand it, their families had fled to Shanghai after the Russian Revolution and then had to flee a second time. I last saw two of them in the early 90s. They were wearing the same old suits but had bright, brand-new sneakers which looked very incongruous. By then they were very old men, tremulously crossing the gangplank onto the Star Ferry, gripping the rail.
In fact Garner continues:
Repel is the verb corresponding most closely in meaning to the adjective repulsive.
Repellent and repulsive both mean, literally, 'causing to turn away.' Repulsive is stronger; it applies to whatever disgusts or offends in the extreme ... Repellent is often more dispassionately descriptive<a sunblock that is repellent to insects>.
I remember when my family lost citizenship in HK in 1997.