| 乙 | yǐ | second of 10 heavenly stems 十天干; second in order; letter "B" or roman "II" in list "A, B, C", or "I, II, III" etc; second party (in legal contract, usually 乙方, as opposed to 甲方); ethyl; bent; winding; radical in Chinese characters (Kangxi radical 5) |
| 乙烯 | yǐ xī | ethylene; vinyl |
| 乙醇 | yǐ chún | ethanol C2H5OH; same as alcohol 酒精 |
| 乙醚 | yǐ mí | ether; diethyl ether C2H5OC2H5 |
| 乙炔 | yǐ quē | acetylene; ethyne C2H2 |
| 乙酸 | yǐ suān | acetic acid (CH3COOH); ethanoic acid |
| 乙二醇 | yǐ èr chún | glycol; ethylene glycol C2H4(OH)2 (antifreeze) |
| 乙烷 | yǐ wán | ethane (C2H6) |
| 乙醛 | yǐ quán | acetaldehyde H3CCHO; ethanal |
| 乙酰 | yǐ xiān | acetyl (chemistry) |
| 乙丑 | yǐ chǒu | second year B2 of the 60 year cycle, e.g. 1985 or 2045 |
| 乙亥 | yǐ hài | twelfth year B12 of the 60 year cycle, e.g. 1995 or 2055 |
| 乙卯 | yǐ mǎo | fifty second year B4 of the 60 year cycle, e.g. 1975 or 2035 |
| 乙型 | yǐ xíng | type B; type II; beta- |
| 乙型肝炎 | yǐ xíng gān yán | hepatitis B |
| 乙型脑炎 | yǐ xíng nǎo yán | meningitis B; epidemic encephalitis B; Japanese encephalitis |
| 乙基 | yǐ jī | ethyl group (chemistry) |
| 乙太 | yǐ tài | ether |
| 乙太网路 | yǐ tài wǎng lù | Ethernet |
| 乙巳 | yǐ sì | forty second year B6 of the 60 year cycle, e.g. 1965 or 2025 |
| 乙方 | yǐ fāng | second party (law); see also 甲方 |
| 乙未 | yǐ wèi | thirty second year B8 of the 60 year cycle, e.g. 1955 or 2015 |
| 乙氨基 | yǐ ān jī | ethylamino group |
| 乙烯基 | yǐ xī jī | vinyl; vinyl group (chemistry) |
| 乙状结肠 | yǐ zhuàng jié cháng | sigmoid colon (anatomy); bent colon, linking the descending colon to the rectum |
| 乙种 | yǐ zhǒng | beta- or type 2 |
| 乙种促效剂 | yǐ zhǒng cù xiào jì | beta-2 agonist |
| 乙种射线 | yǐ zhǒng shè xiàn | beta ray (electron stream from radioactive decay) |
| 乙种粒子 | yǐ zhǒng lì zǐ | beta particle (electron, esp. high speed electron emitted by radioactive nucleus) |
| 乙肝 | yǐ gān | hepatitis B |
| 乙脑 | yǐ nǎo | meningitis B; epidemic encephalitis B; Japanese encephalitis; abbr. for 乙型脑炎 |
| 乙酉 | yǐ yǒu | twenty second year B10 of the 60 year cycle, e.g. 2005 or 2065 |
| 乙酰胺吡咯烷酮 | yǐ xiān àn bǐ luò wán tóng | piracetam (C6H10N2O2) |
| 乙酰胆碱 | yǐ xiān dǎn jiǎn | acetylcholine ACh (amine related to vitamin B complex) |
| 乙酸基 | yǐ suān jī | acetyl radical CH3COO- |
| 乙酸根 | yǐ suān gēn | acetyl radical CH3COO- |
| 乙酸盐 | yǐ suān yán | acetate CH3COO- |
| 乙醇酸 | yǐ chún suān | glycolic acid C2H4O3 |
