Collins Chinese Dictionary Plus (3rd edition), 2011:
可以 kěyǐ
I 助动
1
(=能够) can
- 别(別)人能做到的,你也可以。 Biérén néng zuòdào de,nǐ yě kěyǐ. If other people can do it, so can you.
2
(=有权) may
- 这(這)个(個)俱乐(樂)部任何人都可以参(參)加。 Zhège jùlèbù rènhé rén dōu kěyǐ cānjiā. Anyone may attend this club.
II 形
1
(=不坏) not bad
- 他乒乓球打得还(還)可以。 Tā pīngpāngqiú dǎ de hái kěyǐ. He's not bad at table tennis.
2
(=厉害) awful
- 今天我忙得够(夠)可以的。 Jīntiān wǒ máng de gòu kěyǐ de. I'm awfully busy today.
可以(kěyǐ) , 能(néng) , and 会(huì) can all be used to express ability and are sometimes used interchangeably. Both 可以(kěyǐ) and 能(néng) can express being able to do something because you have been granted permission, e.g. 你可以/能借我的照相机(nǐ kěyǐ/néng jiè wǒ de zhàoxiàngjī) (you may/can borrow my camera). Strictly, 能(néng) should be used to express physical ability, e.g. 我能跑得很快(wǒ néng pǎo de hěn kuài) (I can run very fast), while 会(huì) should express a learned ability, e.g. 我会说法语(wǒ huì shuō Fǎyǔ) (I can speak French).