It refers to words that are stressed on the first syllable.
The stressed syllables in the word "poacher" are "poa" and "cher".
The first.
The first syllable of camera is stressed. No other syllables are stressed.
The first syllable.
The first.
The first syllable is stressed: BAF-fle.
Enemy is stressed on the first syllable.
One - the first syllable is stressed.
The word popular has three syllables. There is one stressed syllable, the first one. The syllables in the word are pop'-u-lar.
In the word "desperate," the stressed syllable is "des" and the unstressed syllables are "per" and "ate." Stressed syllables are pronounced with more emphasis and are typically longer and louder than unstressed syllables.
The first syllable is stressed. The second is unstressed.
Just the first.