Which can help readers define a words?

Etymological patterns
Parts of speech
Stressed syllables
Pronunciation

All of these options can help readers define words, but in different ways:

1. Etymological patterns: Understanding the origins of words and their historical meanings can often provide insight into their current definitions. Etymology can reveal connections between words from different languages and help readers make educated guesses about the meaning of unfamiliar terms.

2. Parts of speech: Identifying the part of speech of a word (e.g., noun, verb, adjective) can provide important clues about its usage and meaning. Different parts of speech often have distinct definitions and can help readers understand a word's role in a sentence.

3. Stressed syllables: Knowing which syllables in a word are stressed can inform readers about its correct pronunciation and also help in determining its meaning. In some cases, the placement of stress can change the part of speech or alter the overall sense of a word.

4. Pronunciation: Accurate pronunciation is essential for understanding the meaning of words. It can also provide additional insights into their origins and help readers recognize related words or derivatives.

Overall, while each of these factors plays a different role in defining words, they are all helpful tools for readers seeking to understand and interpret unfamiliar vocabulary.