The following declension was used for most masculine and neuter nouns. It had also come to be used for female proper names, but normal feminine nouns used a separate declension, seen further below. Most nouns had "-s" in the genitive singular. This was extended to "-es" when it would have caused an awkward-to-pronounce combination of sounds otherwise ("huis", gen. sg. "huizes"), but it was also used occasionally for nouns that didn't require it. If the noun ended with a long vowel, then an apostrophe was included as in modern usage. The "-e" of the dative singular was frequently dropped. Some masculine and neuter nouns became feminine in the dative singular. See below under "mixed nouns". The plural could end in either "-en" or "-s". A few had plurals in "-eren" ("kind", pl. "kinderen"). This is the same as in modern Dutch, see Dutch grammar for more details. Some nouns retained a weak genitive in the singular, including nouns with a nominative sg. in -e and substantivised adjectives. Examples are "mens" (man), "bode" (courier), and "dappere" ("brave one"). Many of the weak nouns were words for people, including "bediende" (servant) "graaf" (count), "heer" (lord), "hertog" (duke), "knaap" (lad), "prins" (prince), "vorst" (prince). "Hart" (heart) belongs to the same group (but see below). Some relics remain of the weak declension in modern Dutch. The cities of 's-Gravenhage (more commonly "Den Haag", The Hague) and 's-Hertogenbosch (Den Bosch) both still show the original weak genitive ending in their names. The Christian expression "dag des Heren" (day of the Lord) also retains it. Feminine nouns had a simpler declension. When separate endings were used, the genitive and dative singular forms would end in "-e". Female proper names did not follow this declension, but were declined as strong masculine/neuter nouns instead. Some nouns mixed several types of declension. The most common irregularity was a feminine dative singular replacing the masculine or neuter one.