It will be argued within this article that 'thermal resistance' is also a serious candidate for this category, at least if the concept is being applied without realizing the differences between thermal and electrical resistances, rather the rule than the exception in practice. The notion of 'thermal resistance' is deeply rooted in the vocabulary of the thermal designer. Usually, these resistances are defined somewhere in the introduction. Of course, it is possible to define everything, and to call it what you want, as long as the expressions at both sides of the equal sign have the same dimensions. There is no law that the definition should make sense from a physical point of view.
Nobody objects to the use of the phrase 'dark light' in a poem.
And here we meet the problem. Unfortunately, the conclusion 'electrical and thermal resistance are analogous' is wrong, while the proposition 'electrical and thermal differential equations are analogous' is right. Mother Nature has to be blamed. This definition is so simple because it is usually applied to single wires, tracks or blocks in which all the streamlines leaving the first node end at the second node. Now, let us try to define thermal resistance in the same sense.