Oh, so many pitfalls. Here are a few more that have crossed the radar recently.
The first means ‘believable’, as in Inconsistencies in the witness’s testimony led inevitably to the conclusion that her evidence was not credible.
The second is sometimes (erroneously) used for credible, perhaps by writers who think that an extra syllable adds weight or effect. Creditable really means ‘reputable’ or ‘bringing credit to’: Irwin Law is a highly creditable publisher of legal titles.
Clearly from the same root, like presume, and sometimes used interchangeably – but best not.
Presumptive should be used when you mean ‘based on inference’ or ‘giving reasonable grounds for belief’, as in Seeing his tax returns might provide presumptive evidence of collusion with Russia.
Presumptuous is usually reserved for situations where you are suggesting that someone is ‘unduly confident’ or ‘impertinent’: It was presumptuous of the junior associate to take a place at the head of the table, where the managing partner usually sits.
Presumptive also has a technical meaning in reference to an heir or heiress whose rights will be displaced by the birth of a nearer heir: During the lifetime of her father, the Queen was only heiress presumptive (not heir apparent) because it was always theoretically possible that her mother might give birth to a son (male primogeniture then being the rule of succession).
This is one I hear, but have yet to see on paper or on screen (give it time, though).
To be wary is to be cautious or leery: I was wary on entering the dive bar; it looked dark and dangerous.
Weary, on the other hand, just means tired: The judge was clearly weary of hearing the long-winded lawyer.
Surprising that they get confused, but they do.