The Chinese word for string is
琴弦

qín xián

Chinese Definition

string
1. 一串，一列；弦，线，绳
Components
琴
1. (musical instrument) qin (“Chinese zithers”), referring to any of several traditional Chinese musical instruments, most famously the guqin
2. (musical instrument) collective name for certain musical instruments, usually of string or keyboard types, such as piano, organ, violin, cello, huqin, accordion, harmonica, etc.
3. (musical instrument, specifically) piano (attn, zh, just Hong Kong?)
4. (Cantonese) yesterday
弦
1. string; bowstring
2. crescent
3. spring of a clock
4. (music) string on a musical instrument
5. (music) stringed instruments or music played by stringed instruments
6. (mathematics) chord
7. (geometry) hypotenuse
8. (figurative) wife

線
1. thread
2. thread-like object; wire; line; string; ray
釣線 - fishing line
電線 - electric wire
光線 - ray of light
3. (geometry) line
4. route; path; line
5. demarcation line; boundary; border; brink
6. clue; sign
7. secret agent
8. ideological or political line
9. plotline
10. (Singapore, computing) network connection
Synonyms: 網
11. (Hong Kong) lane (of a road)
Synonyms: 車道
12. usage. 綫 is preferred in Hong Kong when representing transportation routes.

线
1. Simplified form of 綫

弦
1. string; bowstring
2. crescent
3. spring of a clock
4. (music) string on a musical instrument
5. (music) stringed instruments or music played by stringed instruments
6. (mathematics) chord
7. (geometry) hypotenuse
8. (figurative) wife

字符串
1. n. (Mainland, Hong Kong, , computing) string (of characters)

串
1. to string together; to link up
2. string; chain; series of objects
3. skewer
串燒 - food roasted on a skewer -
羊肉串 - mutton kebab -
一串珠子 - a string of beads -
一串鞭炮 - a string of firecrackers -
一串葡萄 - a bunch of grapes -
4. to cross; to criss-cross; to traverse to; to mix (undesirably)
5. (literary, or in compounds) to gang up on; to conspire; to collaborate
6. to pay a visit to; to visit; to move about
7. (literary, or in compounds) to play a role; to act; to perform
客串 - to give a guest performance -
8. (chiefly Taiwan Internet) thread
9. (Cantonese) to spell a word in Roman letters
10. (Cantonese, slang) cocksure; arrogant; cocky
(Alternative form 寸)
11. (Cantonese, slang) to humiliate; to provoke
(Alternative form 寸)
12. Only used in 串夷