Synonyms for Introductory (same or very similar meaning)
WordNet sense 1 (serving as a base or starting point):
basic
WordNet sense 2 (preceding all others in time or space or degree):
first
WordNet sense 3 (first or beginning):
opening
WordNet sense 4 (serving as an introduction or preface):
prefatory, prefatorial
WordNet sense 5 (existing or coming before):
preceding
From the ODE community, based on WordNet
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