According to Nyaya (Classical Indian School of logic) the fallacy of irregular…

Concept. In Nyaya inference, a reason (hetu) proves a property (sadhya) only when an invariable concomitance (vyapti) links them: wherever the reason occurs, the property must occur. A hetvabhasa is an apparent reason that violates a condition required for valid inference.

Application. An irregular middle does not remain invariably connected with the property to be proved, so it can support incompatible conclusions or fail to settle one conclusion. Nyaya calls this fallacy savyabhicara, also known as anaikantika; therefore the term asked for here is Anaikantika.

Contrast. The remaining terms identify different defects in a reason:

• Asiddha concerns a reason that is not established in the subject or whose required basis is unproved.

• Satpratipaksa concerns a reason counterbalanced by another valid reason that supports the opposite conclusion.

• Badhita concerns a conclusion defeated by a stronger means of knowledge, such as direct perception.

Result. The fallacy of the irregular middle is Anaikantika.