The term K-12 SUBJ. is an abbreviation for a K-12 Subject Teacher, which is a teacher who specializes in teaching subjects such as math, science, and language arts to students in kindergarten through 12th grade. The crossword solution for this term is ENG, which stands for English. An English teacher in a K-12 setting would be responsible for teaching students the fundamentals of the English language, including grammar, reading comprehension, and writing.