June 26: Poole’s word for the day is a bewitching one: haecceity (apparently pronounced as “hike-evity), which had usage long ago as “the property of being a unique and individual thing” or this-ness. Matters are confusing. Haeccity isn’t the same as essence or quiddity, but is more specific, and Poole puts it thus: “How do you describe the dogness of your dog, or the rockness of that rock?”
Someone read to me the word sunder, which means “split apart.” Most often we see it as sundered. Uranium atoms fission in a reactor. Should they sunder?
Source: A Word for Every Day of the Year by Steven Poole.