rucksack (also backpack) noun
VERB + RUCKSACK pack | unpack | put on, shoulder | pull off, remove, take off | carry, have on, wear He had a large rucksack on.
PREP. in a/the ~ He had very little in his rucksack.
You can also check other dicts: rucksack (English, 中文解释 ), wordnet sense, Collins Definition