splinter

(noun) a small thin sharp bit or wood or glass or metal. Synonyms: sliver. Examples: "He got a splinter in his finger." "It broke into slivers."

(verb) withdraw from an organization or communion. Synonyms: secede, break away. Example: "After the break up of the soviet union, many republics broke away."

(verb) divide into slivers or splinters. Synonyms: sliver.

(verb) break up into splinters or slivers. Synonyms: sliver. Example: "The wood splintered."