びっくりして開いた口が塞がらなかった。

to be surprised; to be amazed; to be frightened; to be astonished; to get startled; to jump; surprise (e.g. surprise party)

to open; to undo; to unseal; to unpack; to bloom; to unfold; to spread out; to open (for business, e.g. in the morning); to be wide (gap, etc.); to widen; to hold (meeting, etc.); to give; to open; to found (nation, dynasty, sect, etc.); to open (a new business); to set up; to establish; to start; to open (ports, borders, etc.); to open (an account); to open up (new land, path, etc.); to clear; to develop; to open (a file, etc.); to extract (root); to reduce (equation); to cut open (fish); to change (kanji into hiragana); to flare (e.g. skirt); to slacken (into a poor posture)

mouth; opening; hole; gap; orifice; mouth (of a bottle); spout; nozzle; mouthpiece; gate; door; entrance; exit; speaking; speech; talk (i.e. gossip); taste; palate; mouth (to feed); opening (i.e. vacancy); available position; invitation; summons; kind; sort; type; opening (i.e. beginning); counter for mouthfuls, shares (of money), and swords

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to be closed; to be blocked; to be healed (e.g. wound); to be shut up; to be clogged; to be plugged up; to be occupied; to be taken (e.g. accommodation)