The Collaborative International Dictionary of English v.0.48:
Collateral \Col*lat"er*al\ (k[o^]l*l[a^]t"[~e]r*al), a. [LL.
collateralis; col- + lateralis lateral. See Lateral.]
1. Coming from, being on, or directed toward, the side; as,
collateral pressure. "Collateral light." --Shak.
2. Acting in an indirect way.
If by direct or by collateral hand
They find us touched, we will our kingdom give . . .
To you in satisfaction. --Shak.
3. Related to, but not strictly a part of, the main thing or
matter under consideration; hence, subordinate; not chief
or principal; as, collateral interest; collateral issues.
That he [Attebury] was altogether in the wrong on
the main question, and on all the collateral
questions springing out of it, . . . is true.
4. Tending toward the same conclusion or result as something
else; additional; as, collateral evidence.
Yet the attempt may give
Collateral interest to this homely tale.
5. (Genealogy) Descending from the same stock or ancestor,
but not in the same line or branch or one from the other;
-- opposed to lineal.
Note: Lineal descendants proceed one from another in a direct
line; collateral relations spring from a common
ancestor, but from different branches of that common
stirps or stock. Thus the children of brothers are
collateral relations, having different fathers, but a
common grandfather. --Blackstone.
Collateral assurance, that which is made, over and above
the deed itself.
Collateral circulation (Med. & Physiol.), circulation
established through indirect or subordinate branches when
the supply through the main vessel is obstructed.
Collateral issue. (Law)
(a) An issue taken upon a matter aside from the merits of
(b) An issue raised by a criminal convict who pleads any
matter allowed by law in bar of execution, as pardon,
diversity of person, etc.
(c) A point raised, on cross-examination, aside from the
issue fixed by the pleadings, as to which the answer
of the witness, when given, cannot subsequently be
contradicted by the party asking the question.
Collateral security, security for the performance of
covenants, or the payment of money, besides the principal
collateral damage, (Mil.) damage caused by a military
operation, such as a bombing, to objects or persons not
themselves the intended target of the attack.
[1913 Webster +PJC]
Bouvier's Law Dictionary, Revised 6th Ed (1856):
COLLATERAL ASSURANCE, contracts. That which is made over and above the deed