Prior to the addition of January and February by King Numa Pompilius around 700 BC, April was the second month of the Roman calendar year – March being the first. Around 450 BC, April slipped into the fourth slot and assigned 29 days. With the introduction of the Gregorian calendar by pope Gregory XIIII in 1582, an extra day was added and thus ‘30 days hath April.’
Though April’s derivation is not certain, a common theory is that the
name is rooted in the Latin Aprilis which
is derived from the Latin aperire meaning
“to open” – perhaps a reference to the opening or blossoming of flowers and
trees, a common occurrence throughout the month of April. Another theory holds
that since months are often named for gods and goddess and since Aphrilis is
derived from the Greek “Aphrodite,” one can surmise that the month was named
for the Greek goddess of love, whom the Romans called Venus.
Around the 5th century AD, the
Anglo-Saxons referred to the month of April as Oster-monath or Eostre-monath, a
reference to the goddess Eostre, whose feast occurred during this month. The
Venerable Bede, a monk from the Northumbrian monastery of Saint Peter, believed
this gave root to the word Easter – most often observed during the month of
April. ( http://blog.dictionary.com/)