- serving or intended to serve as an explanation 
WordReference Random House Learner's Dictionary of American English © 2025
ex•plan•a•to•ry /ɪkˈsplænəˌtɔri/USA pronunciation  
adj. 
WordReference Random House Unabridged Dictionary of American English © 2025- serving to explain: an explanatory footnote.
ex•plan•a•to•ry 
(ik splan′ə tôr′ē, -tōr′ē),USA pronunciation adj. 
 ex•plan′a•to′ri•ly, ex•plan′a•tive•ly, adv. 
- serving to explain:an explanatory footnote.
- Late Latin explānātōrius. See explain, -tory1
- 1610–20
Collins Concise English Dictionary © HarperCollins Publishers::
'explanatory' also found in these entries (note: many are not synonyms or translations):
-atory
 - Masorah
 - account
 - annotate
 - annotated
 - annotation
 - appendix
 - comment
 - commentary
 - commentate
 - declarative
 - demonstrative
 - envoy
 - essayistic
 - exegetic
 - explicative
 - exposition
 - expository
 - figure
 - footnote
 - gloss
 - gloze
 - hermeneutic
 - illustrative
 - interpretive
 - legend
 - liner note
 - note
 - over
 - parenthesis
 - rubric
 - schedule
 - scholium
 - self
 - self-evident
 - self-explanatory
 - subtitle
 - synonymy