In Exodus 12:18, the period for eating unleavened bread begins with the evening of the
sunset of the 14th day, which begins the 15th day.  Always note the difference between
the 11 times the bible uses "between the evenings" and when the general word for
"evening" is used.  Sometimes the <general> word for evening is used to refer to
"between the evenings,” if that has already been established in the context, but most of
the time it is used to refer to the evening of sunset, or the second evening.  This word
#06153 can mean <evening> or <sunset>.  Here the word means sunset.  The Israelites
were to eat unleavened bread from sunset on the 14th until sunset on the 21st.

Ex 12:18 In the first month, on the fourteenth day of the month at even, ye shall eat unleavened bread,
until the one and twentieth day of the month at even.

Leviticus 23.32 also uses the <general> word for evening.  The evening of sunset is obvious because
we are speaking of when a day begins and ends.

Leviticus 23:32 It shall be unto you a Sabbath of rest, and ye shall afflict your souls: in the ninth day
of the month at even, from even unto even, shall ye celebrate your Sabbath.

Some words are so general that we can “bend” them.  In the New Testament we see this
with the word <artos> – the <general> word for bread.  If we say "artos" – we think of
regular leavened bread.  However, unleavened bread is still bread.  It is the same with the
word <evening>.  When we say evening, we think of the evening that begins with sunset.  
However, the evening of noon is also evening.  The bible seldom uses the word artos as
unleavened bread.  Similarly, the bible seldom uses evening as the evening of noon
(between the evenings) in the Bible.  We cannot ignore the fact that it does exist,
however.  When the bible uses a general word, the context has to give us more
information in order for us to be sure what it is saying; otherwise, we select the more
common usage of the term.  We have an established relationship when one part of the
bible determines the context for an event – gives the specific term – and then uses a
general term for the same event in another place.  One must study the bible to gain depth
of understanding.

2 Timothy 2:15 Study to shew thyself approved unto God, a workman that needeth not to be ashamed,
rightly dividing the word of truth.