以下
1
not exceeding ...;not more than ...;... and under;... and below;... or fewer
Antonym:
以上 (いじょう)
１６歳以下の子供は劇場には入場できません。
Children of age sixteen and under will not be admitted to the theatre.
2
below (a standard, level, etc.);under;beneath;less than
君の要約は平均以下だね。
Your summary is not up to par.
3
the following;the below-mentioned;the rest;followed by ...
以下の説明は多くの異なる理論を比較的対照することによって得られたものである。
The explanation below was achieved by comparing and contrasting a variety of different theories.
4
including ...;... and other (employees, officials, etc.)
used to refer to all members of a group, starting with the head or principal figure
Other forms
已下 【いか】 (rarely used kanji form)