Ideasthesia is the argument that many synesthesias run on meaning. The evidence: an ambiguous squiggle takes the color of whichever letter context says it is; a numeral’s color follows its value, not its font. The inducer that matters is the concept.
The term, coined by researcher Danko Nikolic, translates roughly as sensing ideas. It reframes classic questions: rather than two senses wired together, synesthesia becomes semantics reaching into perception.
The bouba-kiki effect shows the general population doing something similar in miniature, mapping meaning onto shape and sound with strong agreement, which makes ideasthesia a bridge between synesthetes and everyone else.