理想 (lǐ xiǎng) as a noun means 'ideal' — a standard of perfection or a cherished goal, more abstract and principled than 梦想 (mèng xiǎng 'dream'), which is a personal aspiration. As an adjective, it means 'ideal, perfect' in the sense of being exactly what one wants, less about flawlessness (完美 wán měi) and more about suitability.