Sanskrit रजस् "sperm, tin, autumn, affection, emotion, passion, impurity, menses (menstrual discharge), dirt, darkness, dimness, mist, clouds, firmament, air, pollen."
1. Most commonly, a reference to one of the three gunas, or qualities of nature. The quality of emotion, energy, craving, attachment, tension, passion, or activity.
"The Risis, the seers of truth classify Sraddhâ (faith) under the three headings: Sâttvik, Râjasik and Tâmasik. The quality Rajas is of red colour, wonderful and is not pleasant; it is the source of all troubles; there is no doubt in this. The intelligent should understand that Rajas has certainly arisen in him, when his mind is filled with hatred, enmity, quarrelsome feeling, pride, stupification, uneasiness, sleeplessness, want of faith, egoism, vanity and arrogance." -S'rîmad Devî Bhâgawatam 3:8
“Brahma said: I shall now declare to you accurately what the quality of Passion (Rajas) is. Injuring others, beauty, toil, pleasure and pain, cold and heat, lordship (or power), war, peace, arguments, dissatisfaction, endurance, might, valour, pride, wrath, exertion, quarrel, jealousy, desire, malice, battle, the sense of meum or mineness, protection of others, slaughter, bonds, and affliction, buying and selling, lopping off, cutting, piercing and cutting off the coat of mail that another has worn, fierceness, cruelty, vilifying, pointing out the faults of others, thoughts entirely devoted to worldly affairs, anxiety, animosity, reviling of others, false speech, false or vain gifts, hesitancy or doubts, boastfulness of speech, praise and criticisms, laudation, prowess, defiance, attendance (as on the weak and the sick), obedience (to the commands of preceptors and parents), service or ministrations, harbouring of thirst or desire, cleverness or dexterity of conduct, policy heedlessness, contumely, possessions, and diverse decorations that prevail in the world among men, women, animals, inanimate things, houses, grief, incredulousness, vows and regulations, actions with expectation (of good result), diverse acts of public charity, the rites in respect of Swaha salutations, rites of Swadha and Vashat, officiating at the sacrifices of others, imparting of instruction, performance of sacrifices, study, making of gifts, acceptance of gifts, rites of expiation, auspicious acts, the wish to have this and that, affection generated by the merits of the object for which or whom it is felt, treachery, deception, disrespect and respect, theft, killing, desire of concealment, vexation, wakefulness, ostentation, haughtiness, attachment, devotion, contentment, exultation, gambling, indulgence in scandal, all relations arising out of women, attachment to dancing, instrumental music and songs – all these qualities have been said to belong to the quality of Passion (Rajas).” - The Mahabharata
2. Rajas can also refer to the feminine aspect of sexual energy, sperm (seed), or semen (seed). Also called lunar sexual energy, as a complement to शुक्र shukra, the solar or masculine aspect.