Longimanous is an unusual word that refers to something or someone with long and thin limbs or fingers. If you're looking for similar words to use in your writing, synonyms like lanky, spindly, gangly or wiry could be useful. Other options might include lean, slender, or gaunt. If you're describing something that is long and thin but not necessarily related to limbs or fingers, terms like thin, elongated, stretchy, attenuated, or sinuous could help you to convey the idea. Ultimately, the synonym you choose will depend on the context and the tone of your writing, so choose wisely!