Kṛṣṇa Consciousness means

"Kṛṣṇa consciousness means to work in full knowledge of one's relationship with the Supreme Absolute, and the perfection of this consciousness is full knowledge of Kṛṣṇa, or the Supreme Personality of Godhead." 
-Bhagavad-gītā As It Is 5.29


"Receiving Kṛṣṇa consciousness means receiving light." 
-Teachings of Lord Kapila Vs 14

"Kṛṣṇa consciousness means always thinking of Kṛṣṇa."
-TQK 8: Let There Be Calamities


"Kṛṣṇa consciousness means always living with Kṛṣṇa in His spiritual planet."
-PoP 9: Destination After Death


"Kṛṣṇa consciousness means one has to follow the footsteps of the devotees, sādhu-mārga-anugamanam."
-Śrīmad-Bhāgavatam 6.1.16 --  Denver, June 29, 1975


"Kṛṣṇa consciousness means it is declaration of fighting with māyā."
-Śrī Caitanya-caritāmṛta, Ādi-līlā 7.149-171 -- San Francisco, March 18, 1967


"Kṛṣṇa consciousness means to follow what Kṛṣṇa says."
-Speech to Devotees -- Vṛndāvana, April 7, 1976


"Krsna consciousness means that whatever condition of life I am in at present, that is Krsna's special mercy upon me."
-Letter to: Madhukara — Bombay 4 January, 1973


"Krsna Consciousness means to be on the platform of deathlessness."
-Letter to: Malati — Los Angeles 7 January, 1974


"Krsna Consciousness means one should be always very much anxious to calculate whether every moment of his life has not been utilized in devotional service."
-Letter to: Yamuna — Los Angeles 2 March, 1970


"Krishna Consciousness means attachment for Krishna and detachment for personal benefit, that's all."
-Letter to: Sri Govinda — Bombay 25 December, 1972


"Krishna consciousness means to increase the number of persons in Krishna  consciousness."
 -Letter to: Kirtanananda — New York 13 April, 1967


"Krishna consciousness means staunch faith both in Guru and Krishna."
-Letter to: Devananda — Delhi 27 September, 1967


"Krishna Consciousness means to get out of the material qualities and be reinstated in the spiritual nirguna activities."
-Letter to: Janardana — Los Angeles 21 January, 1968


"Krishna Consciousness means practical living, not something utopian or idealistic and vague. We simply do the needful, whatever pleases Krishna most, that's all."
-Letter to: Yajnesvara — Bombay 2 January, 1972


"Krishna Consciousness means we should always be satisfied and happy, not that we must work something impossible, becoming overburdened, and then because we are unhappy by so much trouble we lose enthusiasm altogether and give up all hope."
-Letter to: Tejiyas — Bombay 19 December, 1972


"Krishna consciousness means that everything including myself are different energies of the Lord and as such should be utilized for the purpose of Krishna."
-Letter to: Alfred Ford — Mayapur 28 October, 1974


"Krishna consciousness means to make one's life successful, as well as helping others to make their lives successful."
-Letter to: Mr. M.K. Kaul — Ahmedabad 28 September, 1975


"Kṛṣṇa consciousness means activity."
-PoP 1: Yoga as Action


"Kṛṣṇa consciousness means to become kind to everyone."
-Bhagavad-gītā 1.21-22 -- London, July 18, 1973


"Kṛṣṇa consciousness means don't try to satisfy your senses."
-Bhagavad-gītā 2.20-25 -- Seattle, October 14, 1968


"Kṛṣṇa consciousness means to understand things as it is. That's all."
-Śrī Īśopaniṣad, Mantra 1 -- Los Angeles, May 2, 1970


"Kṛṣṇa consciousness means he does not anymore eat anything which is not offered to Kṛṣṇa."
-City Hall Lecture -- Durban, October 7, 1975


"Kṛṣṇa consciousness means good-bye to this material world."
-Lecture Excerpt -- London, July 25, 1976


"Kṛṣṇa consciousness means all activities plus God. That's all."
-Lecture -- Seattle, October 11, 1968


"Kṛṣṇa consciousness means Bhagavad-gītā."
-Lecture — Los Angeles, July 11, 1971 (New-2003)


"Kṛṣṇa consciousness means to have all kinds of knowledge."
-Bhagavad-gītā 7.2 -- San Francisco, September 11, 1968