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.
- carbonium ion
- carbonization
- carbonize
- carbonizer
- carbon monoxide
- carbon nanotube
- carbon-neutral
- carbon-nitrogen-oxygen cycle
- carbonous
- carbon paper
- carbon process
- carbon star
- carbon tetrachloride
- carbonyl
- carbonylic
- carborane
- Carborundum
- carboxy-
- carboxyhemoglobin
- carboxyl
- carboxylase
- carboxylate
- carboxylation
- carboxylic
- carboxylic acid