Time sensitivity was an ability possessed by individuals or species that were sensitive to the ebb and flow of time. Tharils were one such species and were highly prized by humans as they could navigate the time lines. Dwarf star alloy was the only substance that could hold time sensitives like Tharils. (TV: Warriors' Gate) Time Lords could detect time sensitivity in others easily. (AUDIO: 1963: Fanfare for the Common Men) The Unnoticed used time sensitives to alert them of the presence of time travellers or planets with time travel capability. (PROSE: The Book of the Still)