primary

first or earliest in a group or series.

main; principal; chief; placed ahead of others.

(geology) Earliest formed; fundamental.

(chemistry) Illustrating, possessing, or characterized by, some quality or property in the first degree; having undergone the first stage of substitution or replacement.

(medicine) Relating to the place where a disorder or disease started to occur.

(medicine) Relating to day-to-day care provided by health professionals such as nurses, general practitioners, dentists etc.