class ActiveSupport::Inflector::Inflections

the rule.
always be a string that may include references to the matched data from
either be a string or a regular expression. The replacement should
Specifies a new singularization rule and its replacement. The rule can

def singular(rule, replacement)
  @uncountables.delete(rule) if rule.is_a?(String)
  @uncountables.delete(replacement)
  @singulars.prepend([rule, replacement])
end