If there was a writing system, with all the letters (let’s assume an alphabetic system) similar to each other, the word shapes would be strenuous to discern from each other.
(A simplistic substitution-cipher for: ‘The cat sat on the mat and the quick brown fox jumps over the lazy dog.’, using various i and t glyphs, and one or two l’s, down at the Latin supplement end of things.)
Where the letter shapes are less similar, it becomes slightly easier to recognise word shapes:
(Same cipher, using random letters from random scripts.)
By comparison, cursive writing, Russian-style, in English:
and in Russian (from the beginning of the Wikipedia article on the solar system):
The conjecture arises that a similar shape-recognition process could be in play for concepts, where nearby concepts on the concept spectrum are interchangeable with each other.
Certainly, a linguistic similarity causes confusion: year versus light-year, Acacia versus Cassia, Lake Constance versus Lake Mungo, etc. And across languages, too, as the false-friends of the translator’s world testify.
Contrariwise, a linguistic difference should make it easy to classify two things as different when they are not (barring some familiarity with the subject matter and a binding classification scheme): up and down (quarks); duck and dodo (birds).
And a third variation tries to make two different things the same by calling them by the same (or similar) names.
Scriptwriters have an increasing tendency of late, presumably from copying each other, of having their characters say: “It’s only circumstantial”, meaning that the evidence at that stage of the plot development is not strong enough to present a case in court and so the hero has to do something more hero-y to obtain it. In real life, anything that is not direct testimony (from a witness) and which proves another fact that goes to the charge is circumstantial evidence (evidence from the surrounding circumstances, such as the presence of DNA) and is often much stronger than direct evidence. Circumstantial evidence is entirely the opposite of ‘only circumstantial’.