The word "illogical" is a common synonym for "unlogical". It means lacking sense or reason and does not logically follow from the facts. Other synonyms for "unlogical" include "irrational", "non-rational", "absurd", "senseless", "groundless", "irrelevant", "inconsistent", and "unreasonable". These words have similar implications as they all describe a situation or argument that lacks logic or reasoning. It is important to use synonyms accurately to convey the right meaning and understanding to the reader, especially when dealing with complex or nuanced topics.