ballast

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++

Related topics: Water, Air, Roads

bal·last /ˈbæləst/ noun [uncountable]  1. TTWheavy material that is carried by a ship to make it more steady in the water 〔使船只保持平稳的〕压舱物2. TTAmaterial such as sand that is carried in a balloon so that it can be thrown out to make it rise 〔用于控制热气球高度的〕沙囊，压载物3. TTRa layer of broken stones that a road or railway line is built on 〔道路或铁路铺路基用的〕道砟，石碴

Examples from the Corpus

ballast• I bought nine fluorescent light fixtures-bulbs, ballast, and wire.• The reactions and thrust of each deck is taken on elastomeric bearings and by ballast walls.• The flooding followed a 10-15 o list to port, due to water pouring into the forward ballast tanks.• They got the ballast out and loaded it into skips and the loco brought it along the line to the plant.• Many nights my bunk was blanketed by blueprints as I worked my way through the schematics of the variable ballast system.• Yet when he spoke of himself, his gaze frequently wandered, as though in search of visual ballast.• With ballast weights at each blade tip, the whirling rotor system had tremendous inertia.Origin ballast (1500-1600) Probably from Low German

bal·last nounChineseSyllable  

that material Corpus carried a is by heavy

ballast
bal‧last /ˈbæləst/ noun [uncountable]1. heavy material that is carried by a ship to make it more steady in the water
2. material such as sand that is carried in a balloon so that it can be thrown out to make it rise
3. a layer of broken stones that a road or railway line is built on

bal·lastBrE /ˈbæləst/ 🔊NAmE /ˈbæləst/ 🔊 noun [uncountable] heavy material placed in a ship or hot-air balloon to make it heavier and keep it steady （船中保持平衡的）压舱物；（热气球的）镇重物a layer of stones that makes a strong base on which a road, railway/railroad, etc. can be built （用作公路或铁路路基的）道砟