As a noun clientness
is {{cx|rare|lang=en}} The state, condition, or quality of a client.
As an adjective clientless is
without a client; lacking clients.
clientness
English
Noun
(-)
The state, condition, or quality of a client.
References
* Google Books: [https://www.google.co.uk/search?tbs=bks%3A1&tbo=1&q=%22clientness%22&btnG=Search+Books&gws_rd=ssl]