Alternative form of ∆: change in a variable
Understanding Δ
• Used on the reaction arrow in a chemical equation, to show that energy in the form of heat is added to the reaction
• Used to represent the symmetric difference (also known as the disjunctive union) of two sets
• Used before a gene name as a modifier to denote a deletion mutation of that gene.
• Used after a pitch class to denote a major seventh chord with a note of said pitch as its root.
(Noun) Abbreviation of defendant.
How Δ affects you
Δ appears in U.S. legal practice across multiple practice areas. Knowing what it means — and when it applies — can determine the outcome of motions, filings, and negotiations. For non-lawyers, the value of looking up a precise definition is that legal terms often carry meanings that differ from everyday usage; relying on the common meaning can lead to costly missteps.
The mechanics of Δ
In practice, Δ is invoked when parties, judges, or attorneys need to identify the legal status of an issue, the rights of those involved, or the procedural step required next. The definition shown above is sourced from Wiktionary , which is widely cited in U.S. legal practice. Because U.S. law is jurisdictionally layered — federal, state, and sometimes local — the precise application of the term can vary by court, so check the controlling authority for your specific case.