suss

Concise Oxford English Dictionary © 2008 Oxford University Press:
suss /sʌs/ Brit. informal

▶verb (susses, sussing, sussed)

• 1 realize.

  ■ understand the true character or nature of.

• 2 (as adj. sussed) clever and well informed.

▶noun

• 1 (also sus) a police suspect.

• 2 knowledge or awareness of a specified kind: business suss.

▶adjective (also sus) shrewd and wary.

– origin 1930s: abbrev. of suspect, suspicion.