CHINK

noun

1. A narrow opening such as a fissure or crack.
2. A chip or dent in something metallic.
3. A vulnerability or flaw in a protection system or in any otherwise formidable system.

verb

1. To fill an opening such as the space between logs in a log house with chinking; to caulk.
2. To crack; to open.
3. To cause to open in cracks or fissures.