[tooth and nail] {adv. phr.} With all weapons or ways of […]

[under construction] {adv. phr.} In the process of being built or […]

[under fire] {adv. phr.} Being shot at or being attacked; hit […]

[under lock and key] {adv. phr.} Secured; locked up; well protected. […]

[under one's belt] {adv. phr.}, {informal} 1. In your stomach; eaten; […]

[under one's breath] {adv. phr.} In a whisper; with a low […]

[under one's heel] {adv. phr.} In one's power or control. * […]

[under one's nose] or [under the nose of] {adv. phr.}, {informal} […]

[under one's own steam] {adv. phr.}, {informal} By one's own efforts; […]

[under one's spell] {adv. phr.} Unable to resist one's influence. * […]