Never trust Merriam-Webster. I don't know if the errors I found are fixed now, but the fact they existed in the first place is disappointing. The only trustworthy English dictionary is Oxford.
Edit: Snuck is a US informal term, according to the backup dictionary, Collins. This dictionary is riddled with ads, but also multiple sources for alternative definitions.
Correct. Thats also what I read. Snuck is irregular, and came about due to common use anyway. So while it’s not correctly following ver typical rules, it’s adopted into the lexicon anyway.
Are you not aware of the different forms of English? There are several differences between American English and British English, "spelled" and "spelt" being one example.
Collins and Merriam-Webster are both American English dictionaries, and the Oxford English Dictionary is a British English dictionary.