Celsius temperature \(t\), \(\theta\)

https://doi.org/10.1351/goldbook.C00928
thermodynamic temperature minus \(273.15\ \text{K}\), invariably expressed in the SI unit degree Celsius(\(^{\unicode{x26ac}}\text{C}\)) which is equal to the kelvin. Sometimes the misnomer centigrade temperature is used for Celsius temperature.
Sources:
Green Book,2nd ed., p. 48 (https://www.cintegrado.com.br/site/documentos/green_book_2ed.pdf)
PAC, 1996, 68, 957. 'Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)' on page 965 (https://doi.org/10.1351/pac199668040957)