The Collaborative International Dictionary
Syphering
Syphering \Sy"pher*ing\, n. [Etymol. uncertain.] (Carp.) The lapping of chamfered edges of planks to make a smooth surface, as for a bulkhead.
Wiktionary
syphering
n. In carpentry, the lapping of chamfered edges of planks to make a smooth surface, as for a bulkhead.