user

One who uses or makes use of something, a consumer or client or an express or implied licensee (free user) or a trespasser.

[Rural solar plant] schemes are of little help to industry or other heavy users of electricity. Nor is solar power yet as cheap as the grid. For all that, the rapid arrival of electric light to Indian villages is long overdue. When the national grid suffers its next huge outage, as it did in July 2012 when hundreds of millions were left in the dark, look for specks of light in the villages.

2019, The Highway Code (United Kingdom) Road Users Requiring Extra Care The most vulnerable road users are pedestrians, cyclists, motorcyclists and horse riders. It is particularly important to be aware of children, older and disabled people, and learner and inexperienced drivers and riders. https://www.gov.uk/guidance/the-highway-code/road-users-requiring-extra-care-204-to-225

A person who uses drugs, especially illegal drugs.

A person who uses a computer or a computing network, especially a person who has received a user account.

Clipping of username.

An exploiter, an abuser (a person who exploits others, that is treats and regards people unfairly, selfishly or unethically).

Someone who uses the R programming language.