We don't have synonyms for block letters yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are block letter, black letters and black letter.
(N) :
(known as printscript, manuscript, print writing, printing or ball and stick in academics) a sans-serif (or "gothic") style of writing Latin script in which the letters are individual glyphs, with no joining.
(N) :
(known as printscript, manuscript, print writing, printing or ball and stick in academics) a sans-serif (or "gothic") style of writing Latin script in which the letters are individual glyphs, with no joining.