We found 8 dictionaries that define the word knock for a loop:

General (4 matching dictionaries)

1. knock for a loop: Merriam-Webster
2. knock for a loop: Wiktionary
3. knock for a loop: Dictionary.com
4. knock for a loop: TheFreeDictionary.com

Business (1 matching dictionary)

5. knock for a loop: Legal dictionary

Computing (1 matching dictionary)

6. knock for a loop: Encyclopedia

Medicine (1 matching dictionary)

7. knock for a loop: Medical dictionary

Miscellaneous (1 matching dictionary)

8. knock for a loop: Idioms

Definitions from Wiktionary (knock for a loop) ▸ verb:  (transitive, idiomatic) To astonish; to stagger or overwhelm; to confuse or disorient. Similar: knock, knock sideways, throw for a loop, knock someone over with a feather, knock about, floor, befuddle, knock someone down with a feather, throw, stagger, more... Opposite: unimpressed, unsurprised, unaffected, unshaken ▸ Words similar to knock for a loop ▸ Usage examples for knock for a loop ▸ Idioms related to knock for a loop ▸ Wikipedia articles (New!) ▸ Words that often appear near knock for a loop ▸ Rhymes of knock for a loop ▸ Invented words related to knock for a loop