tubelight

• tube light

tube +‎ light. The "dim-witted person" sense arises from their flickering as well as the length of time it takes for one to light up completely after being switched on.

• IPA^(key): /ˈt(j)uːbˌlaɪt/

• Audio (Southern England)

  (file)

tubelight (plural tubelights)

1. (chiefly India, South Asia) A fluorescent lighting tube.
   • 2009, A. Subramanyam, Electronics Projects, volume 7, New Delhi: EFY Group, →ISBN, page 55:

     Tubelights can be very troublesome at times. They flicker on and on but refuse to glow.

   • 2021 April 4, “Here’s why Gwyneth Paltrow’s application of sunscreen in a recent video is highly misleading”, in The Indian Express‎:

     "Sunscreens protect you from UVA/UVB rays which can be emitted from many sources of light such as the sun, your tubelight and devices," Dr Khan said, adding that using sunscreen once a day is the bare minimum you can do for your skin.

2. (chiefly India, slang) a dim-witted person; someone who is slow to understand or reply.
   • 2020 February 7, “Tubelight and other insults”, in Deccan Herald‎:

     And Modiji, also being Snarkyji, described Rahulji as a tubelight because Rahulji had interjected only a good 40 minutes after Modiji had launched into his Parliamentary speech.

“tube light”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.