Interpretation Act 2005 section 18

General rules of construction

Section 18 sets out the general rules for interpreting the language used in legislation, covering matters such as singular and plural words, gender references, the meaning of "person", adopted children, distances, time periods, and the legal status of marginal notes and headings.

• Singular words include the plural and vice versa; masculine terms include the feminine (and, for legislation from 22 December 1993 onwards, feminine terms also include the masculine); and "person" includes companies, other bodies, and individuals.
• References to a person's child include adopted children (under the Adoption Acts 1952 to 1998), and for legislation from 14 January 1988 onwards, also include children adopted outside the State whose adoption is recognised under Irish law.
• Distances are measured as a straight line on a horizontal plane; time periods that begin on or end on a specified day include that day; and references to a specific hour are determined by reference to the Standard Time (Amendment) Act 1971.
• Marginal notes, shoulder notes, and headings in legislation are not treated as part of the enactment and cannot be used to interpret it; and where a consecutive series is described by its first and last items, both the first and last are included.