What do we mean by "Ohmic"?

a. "Ohmic" is when the plot of V [Volt] versus I [Amp] yields a linear relationship through the origin, or function.
b. For each current there is one voltage value associated with it. "Ohmic" is when the plot of V [Volt] versus I [Amp] has a slope equal to 1/R.
c. "Ohmic" is when the plot of I [Amp] versus V [Volt] has a slope equal to R.
d. "Ohmic" is when a device does not allow current flow; it is an insulator not a conductor.