椰 is a bound form (b.f.) that cannot be used alone — it always appears as a morpheme in compound words, most commonly 椰子 (yēzi, 'coconut'). You'll also see it in 椰奶 (coconut milk), 椰树 (coconut palm), and 椰汁 (coconut juice). Learners should treat it like a building block rather than a standalone word.