Pro Forma vs. Proforma vs. Pro-Forma
For the general English expression, major dictionary treatment favors the two-word form “pro forma.” Cambridge also records “proforma invoice” as a variant within that business compound, so the closed form should not be generalized into a universal spelling rule.
Use “pro forma” as the general form. “Proforma” is recorded in some compounds such as “proforma invoice”; do not assume “pro-forma” or “proforma” is the universal default.
Key details
Further guidance
Compound Boundary
Cambridge separately records “proforma invoice” as a variant, showing that the closed form can occur in established compound usage rather than serving as a blanket replacement for “pro forma”.
General Form
For ordinary uses of the Latin-derived expression in English, “pro forma” is the clearest default because that is the dictionary headword.
Hyphen Boundary
A hyphen may appear in particular edited compounds or house styles, but the main dictionary headword does not make “pro-forma” the general default.
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.
- Pro forma — English meaning (opens in a new tab)Cambridge University Press · Dictionary headword, word class and current usage of “pro forma”
- Pro forma invoice — English meaning (opens in a new tab)Cambridge University Press · Dictionary attestation of “pro forma invoice” and the recorded “proforma invoice” variant