A word used to make up for gaps in
conversation, when the speaker is not certain what they want to
say next. Can be very annoying if used excessively.
Prime examples include: er, um, erm, and uh
Person 1: What's a
black hole?
Person 2: Black holes are...um...they're uh...black holes, they...erm...er...
Person 1: You have no
fucking clue, do you? You're just using
filler words now.