Solely means for one reason or person alone and no other. Solely responsible, solely because, rely solely on.
It is stronger and more formal than only and sits in contracts, findings and complaints: solely responsible for the loss, solely at the buyer's risk. Solely because introduces a single cause and usually a disputed one. Note the difference from merely, which means no more than, and from wholly, which means entirely — solely restricts the number and wholly restricts the degree, and the two get swapped often.
1adverbsolelyFor one reason or person alone and no other.
“The decision to close the shop was made solely by the owner, without asking the staff.”
synonyms: only, exclusively
solely is a manner of exclusiveness.
Also accepted in games: only, exclusively
Sole plus -ly, from Latin solus, alone. The foot sole and the fish sole are a different Latin word, solea, meaning a sandal.
Middle English
soly
English, today
solely
From Middle English soly, sooly, soolly, equivalent to sole + -ly.
Etymology from Wiktionary, CC BY-SA