Sometimes you will see a crossword clue with one of the following terms appended to it. These terms are conventionally used by crossword compilers to briefly indicate the type of word that the clue is describing.

"Abbr" : Abbreviation. The answer to the clue may be an acronym or contraction that has come into use as a word in its own right. (e.g. "scuba")

"Arch" : Archaic. The answer to the clue is a word that's no longer in common use, or which no longer has its former meaning. (e.g. "forsooth")

"Inf" : Informal. The answer to the clue is a slang term or nickname. (e.g. "gumshoe")