This "movable" prefix "s-" appears at the beginning of some Indo-European roots, but is absent from other occurrences of the same root. For example, the stem "", perhaps 'aurochs', gives Latin "taurus" and Old English "steor" (Modern English "steer"), both meaning 'bull'. Both variants existed side by side in PIE, with Germanic preserving the forms as "*steuraz" and "*þeuraz" respectively, but Italic, Celtic, Slavic and others all have words for 'bull' which reflect the root without the s. Compare also: Gothic "stiur", German "Stier", Avestan "staora" (cattle); but Old Norse "þjórr", Greek "tauros", Latin "taurus", Old Church Slavonic "turъ", Lithuanian "tauras", Welsh "tarw", Old Irish "tarb", Oscan "turuf" and Albanian "taroç".