What is the part of stressed word?

Answer 1

Reckless \ˈre-kləs\, like many words with the -less suffix, is pronounced with stress on the first syllable ie: RECK-less, SENSE-less, HOPE-less, etc.

Answer 2

The part of a word that receives stress is called the stressed syllable. In English, this is typically the syllable that is pronounced with greater emphasis or force compared to the surrounding syllables in a word. Stress can affect the pitch, duration, and volume of a syllable.