横から口を挟む

よこからくちをはさむ

to butt into a conversation (from someone uninvolved)

横

よこ

horizontal (as opposed to vertical), lying down

横にらみ

よこにらみ

sharp-sidelong glance, glare

横面

よこつら よこめん

side of face

横帆

おうはん

square sail

横縞

よこじま

horizontal stripes, lateral stripes

横風

おうふう よこかぜ

cross wind

横軸

よこじく

abscissa, horizontal axis

横波

よこなみ

side (transverse) wave, broadside sea

真横

まよこ

directly horizontal, right beside

横雲

よこぐも

wall or bank of clouds

横転

おうてん

toppling sideways, turning sideways, falling over sideways

横根

よこね

bubo (inflamed swelling in a gland)

横寝

よこね

sleeping on one's side, lying on one's side

横線

おうせん よこせん

horizontal line, abscissa

横車

よこぐるま

perverseness, obstinacy, something unreasonable (like pushing a cart from the side (instead of from behind))

横臥

おうが

lying on one's side

横道

おうどう よこみち

byway, side street, cross street

専横

せんおう

arbitrariness, despotism, tyranny