(dated) The katakana syllable ヰ (wi). Its equivalent in hiragana is ゐ (wi). It is the forty-fifth syllable in the gojūon order; its position is ワ行イ段 (wa-gyō i-dan, “row wa, section i”).

difficult / hard, probably impossible

to use / to employ / to make use of, to apply / to spend

reading / (figuratively) understanding of something, speculation about something

to read (look at and interpret written text) / to read (speak aloud written text) / to infer; to speculate / to count

use one thing for many purposes / work someone hard

to use one's head

be accustomed to reading

A reading of a kanji that is commonly accepted, but originally based on a corrupted reading.

(linguistics) a reading pattern for kanji-compound words, using the Chinese-derived on'yomi for the first portion, and the native Japanese kun'yomi for the second portion