刺激
しげき · shigeki · JLPT N3 · noun
stimulation
⚡ 刺激 = pierce (刺) + violent, intense (激): a sharp jolt that spurs you
刺 means to stab or prick, as in 刺す (sasu) and 刺身 sashimi. 激 means fierce, as in 激しい (hageshii). A stimulus is a fierce prick that provokes a reaction. Sound hook: shigeki is a SHarp, EAGER KEY that switches you on.
刺 — thorn 朿 (phonetic) + knife 刂 (meaning)
A semantic-phonetic compound. The knife radical 刂 carries the meaning of cutting or piercing, while 朿 (a thorn) supplies both the sound and reinforces the idea of something sharp. Original sense was 'to stab' or 'pierce', later extended to 'thorn', 'sting', and figuratively 'to criticize sharply'.