sharp

be as sharp as a tack (American)

to be very intelligent. He may be old, but he's still as sharp as a tack.

See also: tack

Look sharp!

1. something that you say in order to tell someone to hurry. Look sharp! We have to leave in five minutes.

2. something that you say in order to warn someone about something. Look sharp! That ladder isn't very steady.

See also: look

the sharp end (mainly British)

the sharp end of an activity or job is the most difficult part where problems are likely to happen. She enjoys the challenge of being at the sharp end of investment banking. (usually + of)

See also: end

a short sharp shock (British & Australian)

a type of punishment that is quick and severe. What young offenders need is a short sharp shock that will frighten them into behaving more responsibly.

See also: shock, short

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(as) sharp as a tack

very intelligent. He may be old in years, but he's still as sharp as a tack and knows what he's talking about.

See also: tack