(Sanskrit चित्त) This Sanskrit word has a huge varieties of meanings in Asian traditions, so the precise meaning can varying depending upon the context in which it is used. In general use, it refers to "mind." Literal meanings include "wish, thought, ninth mansion, thinking, aim, intention, reason, observing, imagining, intelligence, mind, reflecting, attending, memory, heart, knowledge."
"Chitta is the sub-conscious mind. It has two layers. One layer for emotion and the other for passive memory. The instinctive mind is the lower nature of human beings. It is the desire-mind or Kama Manas. The spiritual mind is the higher Manas. The seat of the mind is the heart. The mind connected to the Somachakra of the lowermost portion or under-surface of the brain is termed the organ of understanding. By Manonasa or annihilation of the mind is meant the destruction or dissolution of the lower nature, desire-mind. Sankhya Buddhi or Buddhi in the light of Sankhya philosophy is will and intellect combined. Mind is microcosm. Mind is Maya. Mind occupies an intermediate state between Prakriti and Purusha, matter and Spirit." - Swami Sivananda, Yoga in Daily Life
"Chitta is termed as the mind-stuff or mental substance. It is the groundfloor, as it were. From it proceed the three Vrittis, viz., Manas, Buddhi and Ahankara. This word belongs to the Rajayogic terminology of Maharshi Patanjali. Also in the Gita, Lord Krishna uses the term Chitta in various places.
"Chitta is a separate faculty or category in Vedanta. Sometimes it is Antargata, comes under Mind. In Sankhya philosophy, it is included in Buddhi or Mahat-Tattva. The Chitta of Patanjali Rishi's philosophy of Raja Yoga (Yogas-chittavritti-nirodhah) corresponds to the Antahkarana of Vedanta.
"Subconscious mind is termed 'Chitta' in Vedanta. Much of your subconsciousness consists of submerged experiences, memories thrown into the background but recoverable. The Chitta is like a calm lake and thoughts are like waves upon the surface of this lake and name and form are the normal ways in which these waves rise. No wave can rise without name and form.
"The functions of the Chitta are Smriti or Smarana, Dharana, attention and Anusandhana (enquiry or investigation). When you repeat the Japa of a Mantra, it is the Chitta that does the Smarana. It does a lot of work. It turns out better work than the mind or Buddhi." - Swami Sivananda, Mind, Its Mysteries and Control