The Spanish word 'pomelo' (meaning grapefruit) comes to us through an interesting journey starting from Dutch. It originated from the Dutch word 'pompelmoes', which was formed by combining two Dutch words: 'pompoen' (meaning pumpkin) and 'limao' (meaning lemon). The name likely came about because the grapefruit resembles a large, pumpkin-sized citrus fruit. The Dutch word was borrowed into English as 'pomelo', and from there it made its way into Spanish, maintaining the same form and meaning.

Unlike many Spanish words, 'pomelo' stands somewhat alone in Spanish vocabulary without many common related words, as it was borrowed relatively recently from English rather than developing from Latin roots shared with other Spanish words.

English speakers will find this word easy to remember since it's identical to the English word 'pomelo', which refers to the same citrus fruit. Both languages borrowed this word through the same path, ultimately from Dutch 'pompelmoes'. The word 'grapefruit' is actually more commonly used in English than 'pomelo', though they can refer to the same fruit.