Liable, open, exposed, subject, prone, susceptible, sensitive are used with reference to persons or things and mean being by nature or situation in a position where something stated or implied may happen.
Liable (see also APT 2 ) ( RESPONSIBLE ) is used particularly when the thing one incurs or may incur is the result of his obligation to authority, of his state in life, or of submission to forces beyond his control.
Open suggests lack of barriers or ease of access.
Exposed presupposes the same conditions as open, but it is more restricted in application because it implies a position or state of peril or a lack of protection or of resistance.
Subject and prone (see also PRONE 2 ) both suggest greater likelihood of incurring or suffering than liable and even less resistance than exposed; they may both connote the position of being under the sway or control of a superior power, but otherwise they differ in implications.
Subject implies openness to something which must be suffered, borne, or undergone for a reason (as a state in life or a social, economic, or political status or a quality of temperament or nature).
Prone, on the other hand, usually implies that the person, or less often the thing, concerned is more or less governed by a propensity or predisposition to something which makes him or it almost certain to incur or to do that thing when conditions are favorable.
Susceptible carries a stronger implication than the preceding terms, with the exception of prone, of something in the person's or thing's nature, character, constitution, or temperament that makes him or it unresistant or liable to a thing and especially to a deleterious thing or a thing that exerts a deleterious influence. When used attributively the word often implies a readiness to fall in love.
Sometimes, however, susceptible stresses openness by reason of one's nature, character, or constitution, rather than liability, and when followed by of is equivalent to admitting or allowing.
Sensitive differs from susceptible chiefly in implying a physical or emotional condition that predisposes one to certain impressions or certain reactions.