ngettext filter-hook . WP 2.2.0

Filters the singular or plural form of a string.

Usage

add_filter( 'ngettext', 'filter_function_name_5001', 10, 5 );
function filter_function_name_5001( $translation, $single, $plural, $number, $domain ){
	// filter...

	return $translation;
}

$translation(string)

Translated text.

$single(string)

The text to be used if the number is singular.

$plural(string)

The text to be used if the number is plural.

$number(string)

The number to compare against to use either the singular or plural form.

$domain(string)

Text domain. Unique identifier for retrieving translated strings.

Where the hook is called

return apply_filters( 'ngettext', $translation, $single, $plural, $number, $domain );

Where the hook is used (in WP core)