proto

adjectives

indicating the first or earliest or original
"`proto' is a combining form in a word like `protolanguage' that refers to the hypothetical ancestor of another language or group of languages"
is similar to
at or near the beginning of a period of time or course of events or before the usual or expected time
"early morning"; "an early warning"; "early diagnosis"; "an early death"; "took early retirement"; "an early spring"; "early varieties of peas and tomatoes mature before most standard varieties"
domain usage
a bound form used only in compounds
"`hemato-' is a combining form in words like `hematology'"