お母さんは目を大きく開いた。

mother

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

eye; eyeball; eyesight; sight; vision; look; stare; glance; an experience; viewpoint; stitch; texture; weave; ordinal number suffix; somewhat; -ish

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

big; large; great; loud

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)