Chardhi Kala (also Chardi kala)
Optimism; the ideal of keeping high spirits, being positive even in times of difficulty, stress, pain and suffering.
A Sikh is to be like the lotus flower: even in filthy water, it remains unsullied (by bad things), pure and beautiful.
Data
Compassion; trying to help others, metta, overlooking people's imperfections and mistakes.
Five Thieves
Also known as the five evils. Five negative personal issues that are considered to rob a person of their better, spiritual nature. A Sikh is expected to subdue these thieves, to ascend them. They are lust (kaam), anger (krodh), greed (lobh), attachment (to material things, etc; moh), ahankar (egotism, pride).
Five Virtues
These are to fight the five thieves, become a better person, and to reach enlightenment. These are truth (sat), compassion (daya), contentment (santokh), humility (nimrata), and love (pyaar).
Kirat karo
One of the Three Pillars of Sikhism. Means earning a living through productive work for the benefit of both the individual and larger society.
Kirtan (also Kirtana, Sankirtan)
A form of religious chanting for purposes of Bhakti practice. Typical but by no means exclusive of the Sikh Faith where is takes the form devotional singing of Shabads, most often from the Sri Guru Granth Sahib and forms the bulk of Sikh religious services.
Langar
The religious practice of eating in community, in equality of conditions (and often of food) for all, including non-Sikhs. Sufism (an esoteric form of Islamic practice) uses the same word with a slightly different meaning.
Manglacharan / Mool Mantar
The first 13 words written in the Sri Guru Granth Sahib Ji (the Manglacharan - from "Ik Onkar" to "Prasad") or the first 13 + the next 12 (the Mool Mantar - from "Ik Onkar" to "hosi bhi sach"). Considered to be a key foundational statement in Sikhi.
Naam Japo
One of the Three Pillars of Sikhism. A form of meditation and chanting aimed to reinforce the connection with God. The word or phrases commonly repeated are "Waheguru", "Satnam Sri Waheguru Ji", or the Manglacharan / Mool Mantar.
Nimrata
Humility; not boasting, not making a big scene, not over-estimating yourself or acting cool.
Pyaar
Love; love of God, and love of humankind. Love is one of the biggest parts of Sikhism.
Santokh
Contentment; not being jealous, being content and not being jealous or envious of others or their possessions.
Seva (also Sewa)
Selfless service; undertaken by a person that is "doing good for the sake of goodness". Within Sikhism, it's divided into material, mental, and physical service.
Vand Chhako
One of the Three Pillars of Sikhism. A practice of sharing of wealth with aspects of reinforcement of community ties.