Adjective
Having a squint.
Having eyes which are in constant motion; shifty-eyed.
Having piercing eyes, sharp-sighted.
Having keen vision.
Source: en.wiktionary.org"Clegg is a gimlet-eyed observer and is masterly at deftly sucking in the reader as he fashions an emotional tsunami into a profound, mesmerizing description." Source: Internet
Yet the honeymoon is coming to an end, and it's time to start balancing our enthusiasm with some gimlet-eyed hard truths. Source: Internet