• 殊更ことさら — deliberately; especially; on purpose
• 特殊とくしゅ — special; exceptional; unique
• 殊勲しゅくん — distinguished merit
• 殊勝しゅしょう — admirable; praiseworthy
• 殊ことに — particularly; especially

殊 uses the radical 歹 and points to what is “set apart” from the rest — something out of the ordinary. Think of a pile where one piece is distinctly different: your eye goes to that exceptional one. That “standing out” is the core sense behind “especially,” “particular,” and “special.”