also: なつめきゅう
noun
night-light bulb; jujube bulb
A small, low-wattage bulb shaped like a jujube fruit, used in night lights or as a dim indicator light.
See also: 棗
寝室にナツメ球をつけて寝る。
I sleep with a night-light bulb on in the bedroom.
この常夜灯にはナツメ球が使われている。
This night light uses a jujube bulb.
From ナツメ (jujube) + 球 (ball/bulb), named for the bulb's resemblance to the jujube fruit.