I asked for answers recently and my eye happened to catch this by chance – it’s all there although I’m not too sure about X. I have Wiki’d xeriscape and the definition is as follows – obviously a list created for gardeners:
The word xeriscaping is a portmanteau of xeros ξήρος (Greek for “dry”) and landscaping, and xeriscape is used for this style of garden. Xeriscaping refers to a method of landscape design that minimizes water use.
Well that doesn’t help! It doesn’t really fit in a list like this. The letter x has come to have much nicer words belonging to it and most importantly of all it signifies a kiss, so I think that is what I will have in my abc.