A Fortiori
From Latin, "with even stronger reason." It 
applies to situations in which if one thing is true then it can be inferred that 
a second thing is even more certainly true. For example, if someone is too young 
to drive, then his younger brother certainly is too young.
A Posteriori
From Latin, applies to a determination derived from or based on inductive 
reasoning or empirical evidence. Involves the flow of reasoning from facts to 
general principals or general causes to effects (as opposed to a priori)
A Priori
From Latin, an assumption based on theory not experiment. For example, an a 
priori assumption would be that the sun will come up tomorrow. (as opposed to a 
posteriori)
Ab Initio
From Latin, "from the start". For example, "The contract was void ab initio."
Abandonment
The act of intentionally and permanently giving something away as referred to a 
child or wife, 2.) relinquishment as referred to a right or estate 3.) careless 
demonstration of freedom (reckless abandonment)
Abatement
(1) in terms of an amount, the taking away, reduction, or allowed discount (2) 
in a situation, the suppression or removal of symptoms. For example, "the 
abatement of pollution."
Abduction
The criminal taking of a person by persuasion, by fraud, or by open force of 
violence.
Abet
To aid, encourage, support, or approve of something. In law, it is usually a 
crime that is being carried out.
Abeyance
Temporary inactivity, cessation, or suspension. In law, it is a state or 
condition of real property in which the title is not as of yet vested in a known 
title holder.
Able-bodied
Having a strong, healthy body. In law, it is often used to describe a person who 
is capable of earning a living and, therefore, able to pay alimony or child 
support.