可以

(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.)

可以

1. can; may

   你不可以走。  ―  Nǐ bù kěyǐ zǒu.  ―  You may not leave.

   這裡可以拍照嗎？ [MSC, trad.]
   这里可以拍照吗？ [MSC, simp.]

   Zhèlǐ kěyǐ pāizhào ma? [Pinyin]

   May I take pictures here?

   • 這人來，為要作見證，就是為光作見證，叫眾人因他可以信。 [MSC, trad.]
     这人来，为要作见证，就是为光作见证，叫众人因他可以信。 [MSC, simp.]

     From: 新標點和合本 (Chinese Union Version with New Punctuation), 約翰福音 (John) 1:7

     Zhè rén lái, wèi yào zuò jiànzhèng, jiùshì wèi guāng zuò jiànzhèng, jiào zhòngrén yīn tā kěyǐ xìn. [Pinyin]

     The same came for a witness, to bear witness of the Light, that all men through him might believe.

2. can; to be able to

   我在哪兒可以弄到電話卡？ [MSC, trad.]
   我在哪儿可以弄到电话卡？ [MSC, simp.]

   Wǒ zài nǎr kěyǐ nòng dào diànhuàkǎ? [Pinyin]

   Where can I get a telephone card?

   現在科學可以說明許多神秘的事。 [MSC, trad.]
   现在科学可以说明许多神秘的事。 [MSC, simp.]

   Xiànzài kēxué kěyǐ shuōmíng xǔduō shénmì de shì. [Pinyin]

   Science can now account for many mysterious things.

   根據他的口音可以判斷出他可能來自下江地區。 [MSC, trad.]
   根据他的口音可以判断出他可能来自下江地区。 [MSC, simp.]

   Gēnjù tā de kǒuyīn kěyǐ pànduàn chū tā kěnéng láizì Xiàjiāng dìqū. [Pinyin]

   From his accent we can infer that he maybe is from the downstream area of the Yangtze River.

3. ... can be used to ... (usually with ellipsed 之 (zhī, “this”)); literally: 可 (“can”) + 以 (“by; by means of; according to”)

   棉花可以織布／棉花可以织布  ―  miánhuā kěyǐ zhībù  ―  cotton can be used to weave cloth (lit. cotton, (one) can by this weave cloth)

   水可以發電／水可以发电  ―  shuǐ kěyǐ fādiàn  ―  water can be used to generate electricity (lit. water, (one) can by this generate electricity)

   • 五畝之宅，樹之以桑，五十者可以衣帛矣。 [Classical Chinese, trad.]
     五亩之宅，树之以桑，五十者可以衣帛矣。 [Classical Chinese, simp.]

     From: Mencius, c. 4^th century BCE

     Wǔ mǔ zhī zhái, shù zhī yǐ sāng, wǔshí zhě kě yǐ yī bó yǐ. [Pinyin]

     (please add an English translation of this usage example)

   • 忠之屬也，可以一戰。戰則請從。 [Classical Chinese, trad.]
     忠之属也，可以一战。战则请从。 [Classical Chinese, simp.]

     From: Commentary of Zuo, c. 4^th century BCE

     Zhōng zhī shǔ yě, kě yǐ yī zhàn. Zhàn zé qǐng cóng. [Pinyin]

     (please add an English translation of this usage example)

   • 它山之石，可以爲錯。 [Classical Chinese, trad.]
     它山之石，可以为错。 [Classical Chinese, simp.]

     From: The Classic of Poetry, c. 11^th – 7^th centuries BCE, translated based on James Legge's version

     Tā shān zhī shí, kě yǐ wèi cuò. [Pinyin]

     The stones from other mountains, can be used as sharpening stones (lit. can make sharpening stones by them)

4. (aviation, Mainland China) to clear; to give clearance

   • 可以起飛 [MSC, trad.]
     可以起飞 [MSC, simp.]

     From: [1]

     kěyǐ qǐfēi [Pinyin]

     cleared for takeoff

• 得以 (déyǐ)

可以

1. passable; pretty good; not bad; all right; OK

   你休息就可以了。 [MSC, trad. and simp.]

   Nǐ xiūxi jiù kěyǐ le. [Pinyin]

   If you rest a while, you'll be alright.

2. to a great extent

   • 這真閑得可以。 [MSC, trad.]
     这真闲得可以。 [MSC, simp.]

     From: 朱自清, 《回來雜記》

     Zhè zhēn xián dé kěyǐ. [Pinyin]

     (please add an English translation of this usage example)

3. capable; remarkable

   你小子可以啊。  ―  Nǐ xiǎozǐ kěyǐ a.  ―  You (affectionate) are remarkable.

可以

1. chữ Hán form of khả dĩ (“possible”).