Equanimity means Unaffectable..
Equanimity means Unprovokable..
Equanimity means Undisturbable..
Equanimity means Unexcitable..
Equanimity means Imperturbable..
Equanimity means Disengaged..
Equanimity means Disentangled..
Equanimity means Detached..
Equanimity means Immovable..
Equanimity means Unbeatable..
Equanimity means Untemptable..
Equanimity means Wholly Immune..
Equanimity means Indifferent..
Equanimity means Impartial..
Equanimity means Unbiased..
Equanimity means Disinterested..
Equanimity means Balanced..
Even like a smiling mountain!
Cool Calm is the ultimate Balm!

The Threefold Equanimity (Upekkhā):
If Indifferent towards both:
Internal states & external phenomena,
Living beings & lifeless things,
Past, present & future events,
How can one be hurt, upset,
disturbed or distressed ?
Calm is his mind.
Calm is his speech.
Calm is his action.
So is the Tranquility;
So is the Equanimity;
of one freed by the Insight
of right Knowledge.
Dhammapada 96

Although a man is richly dressed and adorned,
if he is in peace, at ease, in equanimity, calmed,
composed, controlled, celibate and harmless
towards all beings, then verily he is a Holy One,
a recluse, a sage ...
Dhammapada 142
Equanimity towards one's own internal states -
that is indeed a link to Enlightenment.
Equanimity regarding external phenomena & conditions -
that is indeed also a link to Enlightenment.
Samyutta Nikāya V Bojjhanga-samyutta.
Such noble friend finally develops
the link to awakening that is Equanimity
during Awareness of in-&-out breathing,
which protect against damaging mental states,
tends to detachment, to ceasing, tends to release
& culminates in complete self-surrender...
If, friends, Awareness of in-&-out breathing,
is so cultivated and so made much of, it is
indeed of great fruit, of great advantage!
One whose Awareness of breathing in-&-out
is perfected, well developed, and gradually
brought to refined growth thus, according to the
teaching of the Buddha, such one illuminates the
entire world, just like the full moon freed from clouds.
Samyutta Nikāya V Anapana-samyutta.
The Blessed One once said:
Now how, Ananda, in the discipline of a Noble One is there
the unsurpassable development of the senses?
There is the case where, when seeing a form with the eye,
there arises in a monk what is agreeable, or what is disagreeable,
or what is both agreeable & disagreeable. He recognizes that:
This agreeable thing has arisen in me, or this disagreeable thing...
or this both agreeable & disagreeable thing, has arisen in me:
And that is constructed, conditioned, coarse & dependently co-arisen!
But this is peaceful, this is exquisite, namely even & equal equanimity!
Instantly, that arisen agreeable or disagreeable thing ceases,
and Equanimity takes its calm stance!
Just as a man with good eyes, having closed them, might open them;
or when open, might close them, that is how quickly, how rapidly,
how easily, no matter what it refers to, Equanimity make
whatever arisen agreeable thing... or disagreeable thing...
or both agreeable & disagreeable thing cease right there,
and Equanimity takes its even stance!
In the discipline of The Noble One, this is called the unsurpassable
development of the senses with regard to visible forms cognizable
by the eye. Similar is the supreme development of the other senses.
MN 152
With the fading of rapturous joy, he remains in equanimity,
aware & alert, still physically sensitive to bodily pleasure.
He enters & remains in the third jhana, of which the Noble Ones
declare: 'In aware Equanimity, one abides in pleasure...'
With the stilling of pleasure & pain as with the earlier disappearance
of elation & frustration, he enters & remains in the fourth jhana:
sole Awareness purified by equanimity, - neither pleasure nor pain -
This is called right concentration...
The elimination of both sensual desires & of discontent,
the ejection of laziness, the calming of all regrets,
just this pure Equanimity being aware of all mental
properties exactly at the moment they appear:
That I call the direct knowledge of release
the breakthrough from ignorance.
Sutta Nipāta V 13: Udaya's Questions
Equanimity is 'Tatra-majjhattata', which designates the evenly balanced
keeping to the moderate middle of all things. It has as characteristic, that
it effects the balance of consciousness and mental properties as a single
function of single taste, which prevents both overt excessiveness and any
lack or insufficiency. Equanimity thereby puts an end to biased partiality by
manifesting moderation well within range of the properly reasoned midway.
Visuddhimagga XIV
The Buddha once explained:
I would make my bed in a charnel ground, with a skeleton for my pillow..
And cowherd boys came up and spat on me, urinated on me, threw dirt at me,
and poked sticks into my ears! While others, exultant & thrilled brought me
offerings of food, caskets of perfume & incense and garlands of flowers!
Yet I do not recall, that I ever showed any partiality towards any of them...
I was the same to them all! Neither arousing any fondness nor any aversion!
This was my ultimate perfection of equanimity...
MN 12 Lomahamsanapariyaya
The Hair-raising Presentation
Cariyapitaka III 15
More on Equanimity (Upekkhā):
http://What-Buddha-Said.net/drops/II/Serene_Equanimity_and_Beyond.htm
http://What-Buddha-Said.net/drops/II/Imperturbable_Equanimity.htm
http://What-Buddha-Said.net/drops/IV/Unshakable_Equanimity.htm
http://What-Buddha-Said.net/drops/III/Equanimity_Upekkha.htm
http://What-Buddha-Said.net/drops/III/Feeding_Equanimity.htm
http://What-Buddha-Said.net/drops/III/Empty_Equanimity.htm

More of the 10 mental perfections (paramis):
http://What-Buddha-Said.net/drops/IV/The_Ten_Perfections.htm
http://What-Buddha-Said.net/drops/The_10_mental_perfections_(parami)_in_three_levels.htm
Even is Equanimity!