障礙[shougai] obstacle
阻礙[sogai] obstruction
妨礙[bougai] disturbance
無礙[muge] free from obstacles

融通無礙[yuuzuumuge] free, unfettered and flexible
障礙者[shougaisha] (physically) handicapped person
縦横無礙[juuoumuge] being as free as the air

意気阻喪[ikisosou] depressed in spirits
険阻[kenso] precipice
戦場航空阻止[senjoukoukuusoshi] battlefield air interdiction
阻む[habamu] to keep someone from doing
阻碍[sogai] obstruction

阻止[soshi] obstruction
悪阻[oso] morning sickness
阻喪[sosou] loss of spirit
阻隔[sokaku] separation
成長を阻む[seichouwohabamu] to hinder the growth of (e.g. plants, someone)