*sol-

also solə-, Proto-Indo-European root meaning "whole, well-kept." 

It forms all or part of: catholic; consolidate; consolidation; holism; holo-; holocaust; Holocene; hologram; holograph; insouciant; safe; safety; sage (n.1) kind of herb; salubrious; salutary; salute; salvage; salvific; salvo "simultaneous discharge of guns;" save (v.) "deliver from danger;" save (prep.) "except;" solder; soldier; solemn; solicit; solicitous; solid; solidarity; solidity; sou.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit sarvah "uninjured, intact, whole;" Avestan haurva- "uninjured, intact;" Old Persian haruva-; Greek holos "whole;" Latin salvus "uninjured, in good health, safe," salus "good health," solidus "solid;" Armenian olj "whole, healthy."