A highly scalable synapse device based ona junctionless (JL) ferroelectric (FE) FinFET is presentedfor neuromorphic applications. The synaptic behaviorsof the JL metal-ferroelectric-insulator-silicon FinFET wereexperimentally demonstrated after verifying the ferroelectric characteristics of the HfZrOX (HZO) film using ametal-ferroelectric-metal capacitor. The fabricated synapseshowed distinguishable polarization switching behaviorswith gradually controllable channel conductance. Fromneural network simulations using the proposed JL FEFinFET as synapses, the pattern recognition accuracy forhand-written digits was validated to be approximately 80%for neuromorphic applications.