This is a word from language class. In English, the parts of a word (syllables) are not all said with the same strength. One part gets pushed harder, louder, longer — that one is stressed. The other parts are said more softly and quickly — those are unstressed. In 'BANana', 'ba' and 'na' at the end are unstressed. Whole words can be unstressed too, inside a sentence: in 'I can DO it', the word 'can' is unstressed and comes out sounding like 'kn', not 'can'. That is why English sounds so fast to Chinese speakers — the unstressed parts get squeezed almost to nothing, and the vowel very often turns into the same lazy 'uh' sound (teachers call it schwa). This is the single biggest reason a listener with good grammar can still miss what a native speaker said: the unstressed words are the ones that disappear. 'Unstressed' is a technical term. Dictionaries, pronunciation books, and teachers use it; you will rarely hear it at a dinner table. Careful: a person who is relaxed is NOT 'unstressed' in normal English — for people we say 'not stressed' or 'relaxed'. This word belongs to sounds.

（語音學）非重音的、輕讀的。談單字時說「非重音節」，談句子時說「弱讀」。注意：形容人放鬆不能用這個字，那要說 relaxed。