-Australian slang term, adjective
(1) To describe a person who may be either of: uncouth, unreliable or unpredictable (or all three). Can be used in the serious or playful sense.
(2) A person who is NOT either of the following: reliable, predictable and/or conventional.
(a) "That Pauline, she's a bit of 'loose unit', if you know what I mean"
(b) Or, as used recently in a media interview by a prominent liberal (Australian conservative party) to describe the antics of his own party's attitudes towards current climate change dissent and general disunity over leader Malcolm Turnbull views, "Many of my colleagues are behaving as 'loose units' and need to show cohesion with the party leader and current discussions on climate change."