Sikh word has been used in Sabd Guru as student/pupil/teaching/or a tuft of hair or head -ਚੇਲਾ, ਵਿਦਆਰਥੀ, ਸ਼ਿਸ਼। ਸ਼ਿਸ਼/ਸਿੱਖ ਦੀ/ਦਾ/ਨੂੰ। ਸਿੱਖਿਆ। ਸਿੱਖ/ਸਮਝ! ਬੋਦੀ, ਚੋਟੀ, ਸਿਰ। A Sikh is the student of truth who understands and live the teachings contained in Sabd Guru (AGGS) in word and spirit at each step of daily life. One must take these teachings until these take you. The mechanical recitation of Nitname and other rituals performed daily etc with out understanding are all superstitions with out any spiritual benefit or ਖੇਪ. It is the development of virtues which makes it a devotional worship says Guru Nanak in his Japji;
Some shave their heads, some keep their hair in matted tangles; others observing silence are yet full of pride. Without loving devotion and enlightenment of the self their minds waver and wander in ten directions.-----Guru Nanak, Raag Maru, AGGS, Page, 1013-5
If a Sikh turns to the Guru with sincere faith, as sunmukh - his soul abides with the Guru. Renouncing selfishness and conceit, he remains always on the side of the Guru; he does not know anyone except the Guru. Says Nanak, listen, O Saints: such a Sikh turns toward the Guru with sincere faith, and becomes sunmukh. -----Guru Amardas, Raag Ramkali, AGGS, Page, 919-18 & 19, & 920-21
Gur saṯgur kā jo sikẖ akẖā­ė so bẖalkė uṯẖ har nām ḏẖi­āvai.Uḏam karė bẖalkė parbẖāṯī isnān karė amriṯ sar nāvai.Upḏės gurū har har jap jāpai sabẖ kilvikẖ pāp ḏokẖ leh jāvai.Fir cẖaṛai ḏivas gurbāṇī gāvai bahḏi­ā uṯẖ­ḏi­ā har nām ḏẖi­āvai.Jo sās girās ḏẖi­ā­ė mėrā har har so gursikẖ gurū man bẖāvai.Jis no ḏa­i­āl hovai mėrā su­āmī ṯis gursikẖ gurū upḏės suṇāvai.Jan Nānak ḏẖūṛ mangai ṯis gursikẖ kī jo āp japai avrah nām japāvai.
One who calls himself a Sikh of the True Guru, shall rise early in the morning hours and meditate on the Akal Purkh's Name. Upon arising early in the morning, he is to bathe, and cleanse himself in the pool of nectar. Following the Instructions of the Guru, he is to chant the Name of the Eternal Akal Purkh. All sins, misdeeds and negativity shall be erased. Then, at the rising of the sun, he is to sing Gurbani; whether sitting down or standing up, he is to meditate on the Name. One who meditates on my Eternal God, with every breath and every morsel of food - that Gur Sikh becomes pleasing to the Guru's Mind. That person, unto whom my God and Master is kind and compassionate - upon that Gur Sikh, the Guru's Teachings are bestowed. Servant Nanak begs for the dust of the feet of that Gur Sikh, who himself chants the Naam, and inspires others to chant it.-----Guru Ramdas, Gauri Ki Var, AGGS, Page, 305
ਹਰਿ ਹਰਿ ਗੁਰ ਮਹਿ ਭਗਤਿ ਰਖਾਈ ॥ਗੁਰੁ ਤੁਠਾ ਸਿਖ ਦੇਵੈ ਮੇਰੇ ਭਾਈ ॥ Har har gur meh bẖagaṯ rakẖā¬ī. Gur ṯuṯẖā sikẖḏėvai mėrė bẖā¬ī.
The Akal Purkh has implanted Its devotional worship in the Guru. When the Guru is pleased, He bestows it upon His Sikh, O my siblings of Destiny.-----Guru Ramdas, Raag Asa, AGGS, Page, 367-12
He who believes in One creator, equality for all, with understanding and deliberation of the Gur Bani contained in AGGS with reflection on its teachings in daily life is a Sikh. The practice of the Sikh faith at present is quite different than what is contained in AGGS on the subject as illustrated above. Of course Sikhs came out of Hindus and definitely did not drop from the sky as the selected ones. Sikh Gurus simplified the faith in One Creator for all and advised to get rid of empty superstitious rituals. Sikh faith is no religion IMHO, it is a set of principles if followed honestly and truthfully will make an individual a better human believing in human equality and finding God in him self says Nanak in his Japji;
Within the mind are gems, jewels and rubies, if you listen to the Guru's Teachings, even once.-----Guru Nanak, Japji, AGGS, Page, 2-12
ਜਾਗਤਿ ਜੋਤ ਜਪੈ ਨਿਸ ਬਾਸੁਰ ਏਕ ਬਿਨਾ ਮਨ ਨੈਕ ਨ ਆਨੈ ॥ ਪੂਰਨ ਪ੍ਰੇਮ ਪ੍ਰਤੀਤ ਸਜੈ ਬ੍ਰਤ ਗੋਰ ਮੜੀ ਮਟ ਭੂਲ ਨ ਮਾਨੈ ॥ਤੀਰਥ ਦਾਨ ਦਇਆ ਤਪ ਸੰਜਮ ਏਕ ਬਿਨਾ ਨਹ ਏਕ ਪਛਾਨੈ ॥ ਪੂਰਨ ਜੋਤ ਜਗੈ ਘਟ ਮੈ ਤਬ ਖਾਲਸ ਤਾਹਿ ਨਖਾਲਸ ਜਾਨੈ ॥ Jaagat Joat Japai Nis Basar Ayk Bina Man Naik Na Aanai.Pooran Prem Partit Sajai Barat Gor Marhi Matt Bhool Na Manai.Ttheerathh Daan Dayaa Tap Sanjam Ayk Binaa Neh Ayk Pashhaanai.Pooran joth jagai ghatt mai thab khaalas thaahi nakhaalas jaanai.
He, who remembers the ever-awakened Light throughout night and day and does not bring anyone else in the mind, and practices his vow with whole hearted affection and does not believe in even by oversight, the graves, Hindu monuments and monasteries; and does not recognize anyone else except One God, not even the bestowal of charities, performance of merciful acts, austerities and restraint on pilgrim-stations; the perfect light of the God illuminates his heart, then one comes to know immaculate Pure from impure.------Guru Gobind Singh Sawaeeya # 1, DG, Page, 712