You can often guess a hard word from context. In 'The path was so treacherous that hikers often fell,' what does 'treacherous' mean?

"Treacherous" means dangerous or hazardous, and the sentence's own context makes that clear: hikers falling on the path is a direct consequence of danger, so the word describing the path must mean something risky. This kind of contextual reasoning — using surrounding clues rather than a dictionary — is exactly how fluent readers handle unfamiliar vocabulary in real reading.

"Beautiful" and "flat" don't logically connect to hikers falling; a beautiful or flat path wouldn't cause people to trip and fall repeatedly, so neither fits the cause-and-effect logic embedded in the sentence.

This skill of inferring meaning from context is precisely what fluent readers rely on constantly, since no vocabulary, however large, covers every word a person will ever encounter — context becomes the fallback dictionary everyone actually uses.