gaffer

Etymology 1

From gaff (“hook”) + -er. * (cinema): The natural lighting on early film sets was adjusted by opening and closing flaps in the tent cloths, called gaff cloths or gaff flaps. * (glass):

noun

1. (film) A chief lighting technician for a motion-picture or television production.
2. A glassblower.
   The apprentice carries a gather of glass on the blowpipe to the gaffer's bench […] 2003, Jennifer Bosveld, Glass Works, page 18

Etymology 2

Likely a contraction of godfather, but with the vowels influenced by grandfather. Compare French compère, German Gevatter.

noun

1. (colloquial) An old man.
   If thou return not, Gammer o'er her pail Will sing in sorrow, 'neath the brinded cow, And Gaffer sigh over his nut-brown ale […] 1845, Thomas Cooper, The Purgatory of Suicides, Book the Fourth, Stanza IX
2. (UK, informal) The leader of a group or team, such as a boss, foreman, coach, or publican.
   And you're here to tell me what's what. Just like your bloody gaffer promised. 2022, Liam McIlvanney, The Heretic, page 117
3. A sailor.
4. (Canada) The baby in the house.