The term True Self is used with respect to a person's identity: The
Self. (In this writeup, I will use capital letters to refer to The Self
and types of Self, even though that is not a common standard.)
We can think of many attributes of a person that identify them to
us: choices, thoughts, feelings, likes, dislikes, abilities,
physical appearance, behavioral tendencies et cetera. We may
also consider these attributes when we think of ourselves in relation to
others.
The True Self is the actual Self. The True Self can be contrasted with
the Self we want to be or the Self we want others to see (the False
Self). If your sense of Self is the same as or close to your True Self,
then you basically have a healthy sense of Self. If your Self image is
not your True Self, you may have a tendency towards self-loathing.
If you present a False Self to others, it does not necessarily mean you
have an unhealthy self image. For example, you may have a healthy
sense of Self even if you consciously present a False Self to other
people. For example, you may present a False Self during a job
interview for the purpose of landing a job. That is, playing a role is different than attempting to become
a role.
In some religious traditions, the notion of the True Self is integral
to spirituality. To see the True Self is to see something
bigger, deeper, more universal than ourselves. For instance, some
Christians believe in the notion that our true will is God's will
and that our True Selves are God-like or Christ-like. (Personally, I
think this idea of the True Self is actually a False Self idea.)
Psychotherapists often refer to the notions of True and
False Selves. For instance, Dr. Alice Miller often refers to the True
Self in her works. For purposes of discussion about the True Self,
Dr. Miller generally focuses on emotion and will. How we feel and
what we want, figure prominently in our development as children and our relationships to our parents.
(This is not to deny that other attributes of self-identity may be
relevant in a relationship.)