bedrock

1. (countable, uncountable, geology, mining, engineering, construction) The solid rock found at some depth below the ground surface.Examples: "The denudation of the land was upon a grand scale. All superficial accumulations were swept away, and the bedrock was exposed."; "Listen! It's big. Only eight to twenty feet to bedrock. There won't be a claim that don't run to half a million."countableuncountable

2. (figurative) A basis or foundation.Examples: "If culture is the bedrock of a society, then language is the cornerstone of culture."; "Now, although like most young people, Godfrey was indolent and evasive of difficulties, fearful of facing troubles also, he had a bedrock of character."; "Many of the bedrock assumptions of American culture — about work, progress, fairness and optimism — are being shaken as successive generations worry about the prospect of declining living standards."countablefigurativelyuncountable

3. (Internet slang, self-harm) The bones.Internetcountableuncountable