Q. Do I not have the hyphenation correct in phrases like “3-D printing” and “2-D projection”? I figure that they feature an abbreviation of the word dimensional being used as an attributive compound adjective, so they do call for hyphenation. I ask because one often encounters the abbreviations styled as 3D and 2D. Am I being overly fussy?
A. Yes! Fussy! Chicago defers for these terms to Merriam-Webster, which enters them without the hyphen (and lists the hyphenated versions as “less common” variants).