这是表示方向的前缀in-，它源于拉丁介副词in，其基本含义是in / into, on / upon或towards。它一般加缀在拉丁动词词根前，构成原生动词或动词词干，在构词中起修饰或加强作用。与表示否定的前缀in-（not）—样，表方向的in-也有il-， im-和ir-三个异体，而且构词规则与否定前缀in-也完全相同。

下面先介绍in-与词根缀合的例子。

include [ in- = in 入；clud = to shut 关；-e=>“to shut in”→] vt. contain; have within itself 包含；包括 / The farm includes 160 acres. 这农场有160英亩地。

inclusion n. 包括，包含；内含物 

inclusive a. 包围住的；包括的，包含的

induce [ in- = into 人；due = to lead 引 ; -e =>“to lead into 引入...”→] vt. lead on; persuade 引诱;劝使 / Advertisements induce people to buy. 广告宣传诱人购物。

inducement n. 引诱；劝诱

inflate [ in- = into 入；flat = to blow 欠；-e=>“to blow into 吹入”→]vt. ① fore gas into 使充气，使膨胀 / Please inflate the tires.请给轮胎充充气。②bringing up (prices or currency)物价上涨；通货膨胀 / They do not agree to inflate paper currency. 他们不同意滥发纸币。

inflation n. 充气；通货膨胀，物价飞涨

inhabit [in-= in 在 …内；habit = to dwell 住→]vt. live in 居住于；栖居于/ Fish inhabit the sea.鱼类栖息于海洋中。

inhabitant n. 居民，住户；常住居民