jitter

Short definition from Wiktionary

Noun

1. 1
   A nervous action; a tic.
2. 2
   A state of nervousness.
3. 3
   An abrupt and unwanted variation of one or more signal characteristics.
4. 4
   A random positioning of data points to avoid visual overlap.
5. 5
   A program or routine that performs jitting; a just-in-time compiler.

Verb

1. 1
   To be nervous.
2. 2
   To position data points randomly to avoid visual overlap.