A manually-operable tool (10) for cutting or severing plastic strapping (26) comprises a housing (12) comprising a base portion or foundation (34), and an upstanding web and rib member (36,38). An insertion slot (28), for permitting insertion of plastic strapping (26) to be cut or severed, is defined between a lower edge portion of the upstanding web member (38) and an upper surface portion of the base portion or foundation (34). A cutting blade (20) is adjustably mounted upon the upstanding web member (38). A manually-manipulable handle (14) is pivotally mounted upon the housing (12), under the influence of a biasing spring (18) such that the handle (14) is normally disposed at an opened inoperative position, and includes a spring-biased pusher element (22) which is pivotally mounted upon the handle (14). The pusher element (22) is biased into engagement with the base portion or foundation (34) of the housing (12) by means of its own biasing spring (30) so as to in effect close or cover the entrance to the insertion slot (28). When plastic strapping (26) is to be cut or severed, the strap (26) is inserted into the insertion slot (28) by engaging the pusher element (22) and thereby causing the pusher element (22) to be moved out of the way against the biasing force of its biasing spring (30). Upon the plastic strapping (26) passing the pusher element (22), the pusher element (22) returns to its normally biased position wherein the pusher element (22) now engages the plastic strapping (26). Manipulation of the handle (14) toward the closed position causes the pusher element (22) to push the plastic strapping (26) into engagement with the cutting edge of the cutting blade (20) whereby the plastic strapping (26) is cut or severed.