'Guacamole,' as one might guess, came to English from Spanish. The Spanish 'guacamole,' still referring to the avocado dip, comes Nahuatl, the language of the Aztecs: 'ahuacamolli,' a combination of 'ahuacatl' (avocado) and 'molli' (sauce or paste).
Other English words from Nahuatl include 'ocelot' from 'ocelotl' and 'chocolate' from 'xocolatl'. Any guesses on what the Nahuatl origin of 'tomato' is? Tomatl. I was hoping that 'potato' would have the same thing going on (potatl), but it's from Taino, a Caribbean language.