From Wiktionary, the free dictionary
Alternative spelling
五月蠅い ( kyūjitai )
The spelling is a form of jukujikun (熟字訓 ), and is used in the novels of Natsume Soseki . The literal meaning of the spelling is 五月 ( “ May ” , the month, normally read gogatsu ) + 蝿 ( “ fly ” , the insect, normally read hae ) + い ( i , a common adjective-forming suffix ) , from the way that annoying and noisy flies tend to swarm in May.[ 1]
For pronunciation and definitions of 五月蝿い – see the following entry.
【うるさい 】
[adjective] [late 900s – Kamakura period ] overwhelmingly thorough ( often in a positive way ) ; excessive, repetitive ( in a negative way )
[adjective] [from early 900s] ( by extension from the "thorough" sense ) so thoroughly knowledgeable and particular about something as to be annoying to others: picky , nitpicking , fussy
[adjective] [from late 900s] pushy , bossy , overly particular and demanding
[adjective] [early 1000s – ???] excellent of technique ( particularly for a performance )
[adjective] [late 1100s – ???] extremely strained , faked , insincere , affected
[adjective] [from early 1100s] oppressive and annoying in a surrounding and overwhelming way
[adjective] noisy , loud
[adjective] annoying , irritating
[adjective] [from early 1900s] troublesome , bothersome , irksome ( usually in reference to having to do something )
[adjective] [from early 1600s] dirty , messy , causing a bad feeling
[interjection] ( figuratively ) shut up ; stop it
(This term, 五月蝿い , is an alternative spelling ( less common ) of the above term.)