IPA: /ˌʌnəˈlʊərɪŋ/
KK: /ʌnəˈlʊrɪŋ/
Not attractive or appealing in appearance or quality.
The unalluring design of the building made it blend into the background.
Unalluring → It is formed from "un-" (meaning not) and "alluring" (from Old French *alurer*, meaning to attract or entice). The word "unalluring" means not attractive or not enticing.
Think of 'not' ('un-') making something 'attractive' ('alluring') — that's why unalluring means not attractive.