slack adj.
1 loose
VERBS be, feel, look, seem | become, go Let the reins go slack. | leave sth Leave the thread slightly slack to allow for movement.
ADV. very | completely Some of the ropes were completely slack. | a bit, fairly, slightly
2 not busy
VERBS be, seem | become | remain The antiques business remained slack.
ADV. extremely, very | a bit, fairly, pretty, rather This season has been pretty slack for local hotels so far.
3 lazy
VERBS be | become
ADV. very | a bit, rather
PREP. in She knew she had been very slack in her church attendance recently.
You can also check other dicts: slack (English, 中文解释 ), wordnet sense, Collins Definition