electric resistance, Math - title
  1. To direct current, the potential difference divided by the current when there is no electromotive force in the conductor.
  2. To alternating current, the real part of impedance.
Source:
Green Book, p. 15
ISO 31-4: 1992
PAC, 1996, 68, 957 (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 971