sep·til·lionth 
(sĕp-tĭlyənth)
(sĕp-tĭlyənth)n.
1. The ordinal number matching the number septillion in a series.
2. One of a septillion equal parts.
sep·tillionth adv. & adj.
- imperially
- imperial moth
- Imperial Valley
- imperil
- imperilment
- imperious
- imperiously
- imperiousness
- imperishability
- imperishable
- imperishableness
- imperishably
- imperium
- impermanence
- impermanency
- impermanent
- impermeability
- impermeable
- impermeableness
- impermeably
- impermissibility
- impermissible
- impermissibly
- impersonal
- impersonality