Basic Guidelines For English Spellings
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1The fact or condition of being infested with insects or other bugs; characterized by the presence of a large number of these.
2Computing
Of software: the fact or condition of being prone to malfunction due to programming errors or flaws; the fact or condition of containing many bugs.
Mid 18th century; earliest use found in Nathan Bailey (d. 1742), lexicographer and schoolmaster. From buggy + -ness.