索 suǒ cable

cable; rope; to search; to inquire

How it came to be

会意 · Meaning + meaning

Two or more parts whose meanings together make the new meaning.

The small seal form joins thread and fibres stripped from a hemp stalk.

Bound morpheme for "cable, rope" and, by extension, "to search/inquire": the free noun for a physical rope/cable is usually 绳索 (shéngsuǒ), not bare 索.
搜索 (sōusuǒ) "to search" is the everyday word for searching online or physically (搜索引擎 "search engine"); 探索 (tànsuǒ) "to explore" is used for exploring ideas, space, unknown fields.
线索 (xiànsuǒ) "clue, lead" is common in mystery/investigation contexts.
不假思索 (bùjiǎ-sīsuǒ) "without a moment's hesitation" is a set idiom for responding instantly.