Sentence:  It is evident ... that the day &#91;Maundy Thursday&#93; was observed, as early as the fifth century, by the solemn celebration of the Lord's supper connected with the ceremony of the washing of feet (<WSD>pedilavium</WSD>). Augustin speaks of the celebration of the Lord's supper as being the more ancient and general custom, and of the <WSD>pedilavium</WSD> as of later introduction and more partial observance. 
Meaning of the word marked with <WSD> tags:  The rite of foot-washing based on the act carried out by Jesus Christ on his disciples at the Last Supper. Depending on the church or denomination, it may be carried out at baptism, during Holy Communion, or as part of a Maundy Thursday service; maundy.