abstruseab‧struse /əbˈstruːs, æb-/ adjective formal 
unnecessarily complicated and difficult to understand: 
Maths is a mix of abstruse theory and detailed calculations.
unnecessarily complicated and difficult to understand: Maths is a mix of abstruse theory and detailed calculations.- impregnable
- impregnate
- impresario
- impress
- impression
- impressionable
- impressionism
- impressionist
- impressionistic
- impressionistically
- impressive
- impressively
- impressiveness
- imprimatur
- imprint
- imprison
- imprisonment
- improbability
- improbable
- improbably
- impromptu
- improper
- improper fraction
- improperly
- impropriety