bulb
- 01 A2 Elementary
n.the glass part of an electric lamp that produces light.
n.the glass housing of an incandescent or LED lamp that emits light when powered.
Simple“The light bulb in the hallway burned out, so we need to buy a new one.”
In context“The energy-efficient LED bulb provides the same level of brightness as a traditional hundred-watt incandescent while consuming significantly less power.”
UsageOften used in the compound 'light bulb'.
- 02 B1 Intermediate
n.the round underground part of some plants, like onions or tulips, where they store food.
n.a rounded underground storage organ in plants, consisting of a short stem covered by fleshy leaves.
Simple“You should plant the tulip bulbs in the autumn so they flower in the spring.”
In context“The gardener carefully separated the lily bulbs to ensure each one had enough space to develop its own root system before the first frost.”
UsageCommonly used in gardening and botany contexts.
Synonymscormtuber - 03 B2 Upper Intermediate
n.any object that is round at one end and thinner at the other.
n.a rounded, protuberant part of an object or anatomical structure.
Simple“The thermometer has a small glass bulb at the bottom filled with red liquid.”
In context“The glassblower carefully shaped the bulb of the wine glass, ensuring the walls were of uniform thickness throughout the curve.”
- 04 C2 Proficiency
n.a rounded part at the front of a ship below the water that helps it move faster.
n.a bulbous protuberance at the bow of a vessel, designed to modify the water flow and reduce drag.
Simple“The large ship has a bulb at the front to help it save fuel.”
In context“The installation of a bulbous bow significantly improved the tanker's fuel efficiency by reducing wave-making resistance during long-haul voyages.”
UsageUsually refers to a 'bulbous bow' in naval architecture.
Teacher's tipThis is a highly specialized term; learners are unlikely to encounter it outside of maritime engineering.
Synonymsbulbous bow - 05 C2 Proficiency
v.to swell or grow into a round shape.
v.to take the shape of a bulb or to swell into a protuberance.
Simple“The base of the plant began to bulb as it matured.”
In context“The glass began to bulb outward under the pressure of the artisan's breath, glowing a fierce orange in the dim workshop.”
UsageIntransitive verb.
Teacher's tipThis verbal use is rare and mostly found in older literature or technical descriptions of growth.
Etymology tree Ancient Greek βολβός (bolbós)bor. Latin bulbusder. English bulb Inherited from Middle English bulb, bolbe, from Latin bulbus (“bulb, onion”), from Ancient Greek βολβός (bolbós, “plant with round swelling on underground stem”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.