how to read 躍?

Brushing up on my Chinese, I came across this character: 躍. “I wonder how you pronounce it,” I said to myself, and tried to look it up under pinyin yào, since it shares the phonetic with 耀 ‘shine’. No dice.

As it turns out, 躍 ‘leap’ is Mand. yuè / Canto. joek6 (or joek3). But in Middle Chinese, it was homophonous with 藥 yào / joek6 ‘medicine’ (they’re listed right next to each other in the Guangyun). They’re still homophonous in Cantonese, but in Mandarin they’ve taken on separate readings. A similar thing happened with 角 ‘corner’ (Canto. gok3), which is sometimes read jiǎo and sometimes jué.

To add to the confusion, here are some more characters with the same phonetic but read differently:

• 耀 yào / jiu6 ‘shine’
• 戳 chuō / coek3 ‘jab, poke’
• 擢 zhuó / zok6 ‘pull out’