Such an everyday thing as annoyance is not seen from the moment the dwarves enter the barrels until Bilbo is safely home in Bag-End.  This is a case of “an-” prefix 1, a particle handy for forming verbs, adverbs, and prepositions.

• 01.058 and annoyed.
• 01.142 (which annoyed Bilbo very much),
• 02.034 was most annoying.
• 02.108 and very annoyed:
• 03.018 or get annoyed with them.
• 05.098 But Bilbo was annoyed at the delay.
• 07.018 and you must be careful not to annoy him,
• 08.049 We are quite annoyed enough with you as it is.
• 09.034 and also rather annoyed.
• 19.035 as Bilbo noticed with annoyance.

“annoy, v.” OED Online. Oxford University Press, March 2015. Web. 18 May 2015.