We don't have synonyms for upcasting yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are casting, recasting and pasting.
(n) :
(computing) A cast from subtype to supertype.
(v) :
(transitive, computing) To cast from subtype to supertype.
(v) :
To broadcast a message or data to aircraft or satellites, especially via radio waves; as opposed to uplinking to a specific satellite or aircraft
(n) :
(mining) The ventilating shaft of a mine out of which the air passes after having circulated through the mine.
(n) :
(computing) A cast from subtype to supertype.
(v) :
(transitive, computing) To cast from subtype to supertype.
(v) :
To broadcast a message or data to aircraft or satellites, especially via radio waves; as opposed to uplinking to a specific satellite or aircraft
(n) :
(mining) The ventilating shaft of a mine out of which the air passes after having circulated through the mine.