Hi, EyeSeeYou,
I don't think we talk about 'voiceless word' but rather 'voiceless sounds', and it does seem a pretty stupid thing to say. How can you speak without a voice?
This is a definition from a guide to English Pronunciation
[link]
VOICELESS SOUNDS
"voiceless sounds are produced with the glottis open
the vocal cords are separated
airflow is free
there is no vibration of the vocal cords
voiceless sounds use more energy
All vowels are voiced sounds.
Consonants can be made with or without the voice. "
VOICED SOUNDS
sounds are produced with the glottis closed
the vocal cords are pressed together
airflow is interrupted
the vocal cords are made to vibrate
voiced sounds use less energy to say
All vowels are voiced sounds.
Consonants can be made with or without the voice.
To feel the difference, try this:
put your hand gently on the front of your throat, where your voice box is. Now hum gently; you should feel the vibration. That's voiced
Now keep your hand on your throat asnd say "sssssssssssssss" through your teeth. That's voiceless.
In other words, if we use our vocal chords to make a sound, it's voiced. If the sound is all made in the mouth, it's voiceless, or "unvoiced"