1) Possibly ‘elder’, the meaning suggested for it as a place-name element by Smith (PNWR7/182), although in contexts where the reference is to underwood it is almost certainly an alternative spelling of ‘alder’.
1380 ‘one wagon-load of Ellerstowrs’, Yeadon
1530 for ij eller powylles to a stey [ladder] and for making vjd ob, York
a.1568 Item solde … as much Eller and other woode, Pickering
1580-1 For iiij loades of ellerwood to the plumber, 12s 8d, York
1688 did borrow an axe for cutting an eller sticke, West Riding
1710 did see Thomas Sharpe fell and carry awaye four eller polls of wood – vulgarly soe called – in a close belonging to Richard Richardson, North Bierley. It must be suspected that most place-names which have ‘eller’ as a first element refer to alder trees, especially when the suffix identifies a wet location. Typical early examples include n.d. Ellerkelde
1387 Ellirsikgate but the most frequent combination is ‘ellercarr’. Ellerker in the East Riding is a major place-name, recorded as early as 1086 but similar names are found over a wide area from the thirteenth century a.1287 le Sykes and Ellerkerr, Hornington
1387 Hellerker, Wensley. The meaning is ‘alder marsh’, but the inference is that the term developed into a generic which referred to a managed ‘alder carr’. In Brandsby, ‘Nelson’s Ellercarr’ was tenanted by Christopher Nelson and several references capture it at a transitional stage, e.g. 1609 Christofer Nelsons man brought greene wodd forth of his Ellicarrs. Om 1621 Richard Cholmeley wrote of his yonge eller carr, Brandsby. Note the by-name: c.1296 William Ellerbayn, Denton, perhaps a nickname making fun of slender, pole-like legs.