Emily Dickinson Lexicon

sill (-s), n. [OE syll.]

1. Window frame; bottom border of a window opening.
2. Arm; base; low-hanging offshoot; horizontal extension of wood; [kenning: “Amber Sill”] oak tree branch; bird's nest in an oak tree.
3. Threshold; [fig.] horizon.
4. Foundation; groundwork; [fig.] basic premise.
5. Cornerstone; secure base; firm footing.