“Peace of mind” is the established expression for a feeling of calm or freedom from worry. “Piece of mind” is not the standard form for that meaning, although “a piece of my mind” is a different expression.
ReviewedEvidence1 sourceSectionPhrases & Idioms
Quick answer
Use “peace of mind” for reassurance or calm: “The backup gives me peace of mind.”
Key details
Canonical Formpeace of mind
Common Errorpiece of mind
Core Meaninga feeling of calm or not being worried
Variants
peace of mind
Dictionary-listed expression for calm or reassurance.
piece of mind
Not the standard expression when calm or reassurance is intended.
Further guidance
Correct Form
Cambridge records “peace of mind” as the established idiom for calm or freedom from worry.
Distinction
Do not confuse it with the separate expression “give someone a piece of your mind,” which has a different meaning.
History Boundary
This guide focuses on current form and meaning and does not claim an absolute first use.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
The established expression is “bad rap,” referring to severe criticism, an unfavorable judgment, or an unfair accusation depending on context. “Bad wrap” is not the standard spelling of that expression; “wrap” has its own unrelated meanings.
The established expression is “with bated breath,” used for waiting in an anxious or excited way. Cambridge records “bated” in this fixed phrase. “Baited breath” is a sound-based spelling confusion, not the form supported by the reviewed dictionary evidence.
The established expression is “at someone’s beck and call,” meaning ready and willing to do whatever that person asks. “Beckon call” is a common mishearing or eggcorn, not the standard form of the idiom.
“Champing at the bit” and “chomping at the bit” are both used for being very eager or impatient to begin. Cambridge explicitly records champing/chomping as variants; “champing” reflects the older horse-related wording, while “chomping” is a widely accepted modern variant.
“Couldn’t care less” means not caring at all and is the clearest form across English varieties. Cambridge also records “could care less” as a US informal variant used with the same intended meaning, despite its literal wording appearing logically opposite.
The established adjective is “deep-seated,” meaning strongly rooted, firmly established, or difficult to change. “Deep-seeded” is a common reinterpretation when this meaning is intended, even though a literal seeded construction can occur in unrelated contexts.
The standard expression is “dog-eat-dog,” describing a situation in which people compete ruthlessly for their own advantage. “Doggy-dog” is a sound-based reinterpretation, not the standard form of the expression.
The established expression is “get away scot-free” or “escape scot-free,” meaning to avoid punishment or a penalty. “Scotch-free” is not the standard form; the word is “scot,” historically connected with a tax or payment.
