The word "animosity" means: feeling of hostility or disgust.
The Lord Jesus Christ calls all his followers (Christians) to love those who show animosity against them. In other words, we must love those who hate us or have a feeling of hostility against us.
In the Gospel of Matthew 5:44, King James Version (NIV), the Lord Jesus said to his disciples:
But I tell you: love your enemies, bless those who curse you, do good to those who hate you and pray for those who outrage and persecute you.
The correct meaning of the word "enemy" is not limited to anyone we don't like. The order to love our enemies means much more than simply changing our feelings about people we don't get along with.
Rather, "enemy" (in Greek echtros) means "adversary" and refers to those whose actions and words manifest hatred towards you; the brother-in-law or sister-in-law who doesn't want to talk to you, the co-worker who wants to be fired.
We are commanded to love those who have animosity. Jesus leaves no room for speculation in this passage we have read, but he sends us to love those who hate us, despise us and persecute us. Such love is only possible through the power of Jesus Christ, who loved that way, and now seeks ways to show his love to those who hate him by besieging disciples like you.