early-term
Word family
Synonym discussion
Sense: adjective/1
All three point to the opening part of something, but they differ in scope. 'Early-term' is the most specific: it describes the first part of a fixed-length stretch of time, above all a pregnancy, and also a leader's time in office or the opening of an illness. 'Early-stage' is broader — it suits anything that grows through clear phases, such as a disease, a company, or a research project, and does not need a set end point. 'Initial' is the most general and least technical word; it simply marks whatever comes first, as in 'initial reaction' or 'initial cost'. So you would say 'an early-term pregnancy', 'an early-stage start-up', and 'an initial guess', and these would rarely swap places without sounding odd.
Common collocations
Etymology
A modern compound formed from 'early', meaning near the beginning, and 'term', which here keeps its sense of a fixed length of time — the same 'term' used for a pregnancy or a period in office. The word 'term' came into English through French from Latin 'terminus', meaning a boundary or limit. Joined together, the pair labels the opening part of such a fixed period.