As nouns the difference between dation and dition
is that dation is (rare|legal) the act of giving, granting or conferring (eg an office) but not liberal as a donation or gift while dition is (obsolete) dominion; rule.
dation
English
Noun
(
en noun)
(rare, legal) The act of giving, granting or conferring (e.g. an office) but not liberal as a donation or gift
(obsolete, medicine) A dose
Derived terms
* dation in payment
References
*OED 2nd edition.