Filler (?), n. 1. One who, or that which, fills; something used for filling.[1913 Webster]
'T is mere filler, to stop a vacancy in the hexameter.
They have six diggers to four fillers, so as to keep the fillers always at work.
2. (Paint.) A composition, as of powdered silica and oil, used to fill the pores and grain of wood before applying paint, varnish, etc.[Webster 1913 Suppl.]
3. (Forestry) Any standing tree or standard higher than the surrounding coppice in the form of forest known as coppice under standards. Chiefly used in the pl.[Webster 1913 Suppl.]
Filler, n. [From 1st Fill.] A thill horse. [Prov. Eng.][1913 Webster]