Word origin · etymology
Modern explanatory English phrase.
Effective is used in the sense operative or in effect. It descends from Middle English effectif and Late Latin effectivus. Here the compound labels a calculation choice; it is not presented as a historical Nine Star term.
How we know · epistemology
Method-dependent intermediate value
The effective year is reproducible only when the boundary rule is known. It is an input to the annual-number arithmetic, not an additional prediction.
Blooming Grove Studio · Nine Star Ki lessons 1–3 ↗NAOJ · Calendar terminology, 24 solar terms ↗
Connected concepts
Terms used in this explanation
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These links connect subjects and terminology. They do not establish a shared historical origin.
Sources & provenance
Use the citations beside each section to distinguish a calculation convention, a historical teaching and an editorial example.