1) Atonic 2) Like the pre in predict 3) Not accented 4) Stress-free 5) Unstressed 6) Used of syllables 7) Used of vowels or syllables 1) Atonic 2) Stressless 3) Unemphatic 4) Unstressed 
[adj] - used of vowels or syllables
light adjective used of vowels or syllables; pronounced with little or no stress; `a syllable that ends in a short vowel is a light syllable`; `a weak stress on the second syllable`
not accented; unstressed.