What does basis mean?
Basis is a noun referring to the underlying foundation, principle, or set of facts on which something is constructed, justified, or carried out. It can describe a literal groundwork — as in the basis of an argument or theory — or a more abstract footing, such as the basis on which two parties negotiate. In everyday usage it frequently appears in the fixed phrase 'on a ... basis', where it expresses frequency or regularity: someone may exercise on a daily basis or review staff performance on an annual basis. The word carries no strong connotation of approval or disapproval; it is neutral, precise, and common across academic, professional, and journalistic writing. Its plural is bases (pronounced /ˈbeɪsiːz/), which can also be the plural of 'base', making context essential. Borrowed directly from Greek through Latin into English, basis has long served as one of those quiet structural words: rarely noticed on its own, yet holding up arguments, systems, and routines throughout the language.
nounThe underlying support, foundation, or principal element on which something is built, reasoned, or established; also the set of circumstances or conditions forming the reason for a decision or action.
- The underlying foundation or fundamental principle on which something is based
- The reason, justification, or grounds for a decision or action
- A regular pattern or arrangement governing how often something happens (as in 'on a weekly basis')
"The committee rejected the proposal on the basis that it exceeded the available budget."
"Trust between the two nations was rebuilt on the basis of mutual respect."
"She visits her grandparents on a monthly basis."
Pronounced /ˈbeɪsiːz/. Note that 'bases' is also the plural of 'base'; context determines which headword applies.
"The study compared data collected on three different bases."
In mathematics, a 'basis' lets you build an entire space from just a handful of vectors — and in English, it does much the same job: everything else rests on it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of basis
Basis comes from the Greek word 'basis' meaning 'a stepping' or 'foundation', derived from the verb 'bainein', 'to go or step'. Latin adopted the Greek term unchanged, preserving its sense of a base or pedestal, and English borrowed it from Latin in the early modern period. The same Greek root gives English words such as 'base', 'basic', and 'basement', all sharing the idea of a bottom or supporting layer.
How basis is actually used
'Basis' is largely formal to neutral in register. It almost always appears in the phrase 'on a/the ... basis' rather than standing alone. The plural 'bases' is pronounced /ˈbeɪsiːz/, distinct in vowel length from the singular.
Easily confused with basis
'Bases' is either the plural of 'basis' or the plural of 'base', whereas 'basis' refers to the single underlying foundation of something.