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.
- specific heat
- specific humidity
- specific impulse
- specificity
- specific performance
- specific resistance
- specific thrust
- specifier
- specify
- specimen
- speciosity
- specious
- speciously
- speciousness
- speck
- speckle
- speckled
- speckled perch
- speckled trout
- specks
- specs
- spectacle
- spectacled
- spectacled bear
- spectacular