Is it legal to redefine a term against common sense in a contract
<p>Can the writer of a contract attempt to trick the signer using defined terms? Is such a contract binding or void, and can the writer get into trouble for doing so (eg. for misrepresentation)? Two types of scenarios that I want to ask about:</p>

<ol>
<li>When a defined term in the contract carry a much narrower, or much broader meaning than the common meaning. For example, can a contract define a term "Image" (as in a picture) to mean any computer file, or to mean any image showing a red flower?</li>
<li>When the defined meaning is completely incompatible with the common sense meaning. For example, can a contract define an "Text file" as a file with the <code>.png</code> extension?</li>
</ol>

<p>Does the answer change if the defined term, when used normally, starts with a capital letter (eg. if "SVG file" is defined as a <code>.png</code> file), so the reader is less likely to suspect the term has been defined in the contract itself?</p>

<p>Does the answer change if this happened in another legal document, such as a EULA, where the person agreeing does not have a chance to call the writer of the document out?</p>

<blockquote>
  <p>Is it legal to redefine a term against common sense in a contract?</p>
</blockquote>

<p>Generally speaking, yes. What matters is that the contract be clear enough for the parties to be aware of the terms and conditions to which they are committing. Both of the scenarios you outline seem lawful. They are binding to the extent that the definitions &amp; language therein duly inform the parties of the substance of the contract. Definitions in a contract are most pertinent where the meaning of a term is intended to supersede and replace the commonplace meaning thereof.</p>

<p>A contract would become null and void if the substance of that contract contravenes legislation. If legislation outlaws not only the effect of a clause but also its meaning, then the [un-]lawfulness of that clause is not altered simply by crafting definitions of terms. In other words, laws or legislative intent cannot be elluded by relabeling concepts in a contract.</p>

<p>Whenever lawful, the attempt to trick a party with tactics (such as the use of uppercase you mention) is likely to be voidable by that party. The rationale is the same: The draftsman's attempt to confuse the user contravenes the contract law tenet that the parties <em>knowingly</em> enter the contract at issue.</p>

<p>Notice that in the preceding paragraph I wrote "<em>whenever lawful</em>" rather than "<em>although lawful</em>". The reason for that choice is that, in some contexts, the draftsman's tricky attempts might constitute a <em>deceptive practice</em> and thus be in violation of the law (for instance, consumer protection laws).</p>

contract-law