What is meant by 'Strength Training' anyway?

So, I am reading another thread about the importance of lifting/strength training while in a calorie deficit to lose weight. Myself, I have about another 28 pounds to lose. 5'9" height, 193 lbs, bust: 40, waist 32, hips 44. I am soooo confused about this. OK - I get the idea of cardio 3x/week. But what do you mean by strength training? I do what I guess can be classified as strength training - resistance training, primarily with bodyweight workouts. I have also added some freeweights (lifting as heavy as I can, to about 7 reps) but I wouldn't say I am following the 5x5 method. So, when you are in weight loss mode, are bodyweight workouts effective as strength training?